Kohlrabi Gratin

This Kohlrabi Gratin casserole is a decadent side dish! It's baked in a skillet with a creamy Gruyere cheese sauce and breadcrumb topping.

When it comes to holiday side dishes, it doesn't get any more delicious than this Kohlrabi Gratin. It's rich and creamy and makes the perfect addition to your holiday dinner table.

Many gratin or au gratin dishes are made with potatoes but this recipe puts a spin on the classic version. It's made with kohlrabi, one of my favorite underrated vegetables.

Much like the potato version, the kohlrabi is thinly sliced and baked in a skillet along with garlic, onions, and a homemade creamy Gruyere cheese sauce. A savory breadcrumb topping is added as well, which provides a crunchy texture.

If eaten raw, kohlrabi has a crunchy texture and the flavor is somewhere between a turnip and a broccoli stem. When cooked, the flavor of the kohlrabi mellows out and becomes sweeter, which complements the decadent cheese sauce perfectly.

I've made both au gratin potatoes and kohlrabi gratin and to be perfectly honest, I prefer the kohlrabi version. I find that the kohlrabi has more flavor than potatoes. It's one of those dishes that I found myself going back for one more bite again and again.

Jump to:

• What Is Kohlrabi?
• Does Kohlrabi Need To Be Peeled?
• How To Peel Kohlrabi
• How To Slice Kohlrabi
• Ingredients For Kohlrabi Gratin
• What Is Gratin?
• How To Make Gruyere Cheese Sauce
• How To Thicken Cheese Sauce
• How To Make The Breadcrumb Topping
• How To Make Kohlrabi Gratin
• How Long Does Gratin Take To Bake?
• What To Serve With Kohlrabi Gratin
• Can This Gratin Be Made Ahead Of Time?
• How Long Does It Last In The Fridge?
• Can It Be Frozen?
• Kohlrabi Gratin

What Is Kohlrabi?

Kohlrabi (also known as a German turnip) is a nutrient-packed vegetable that can be eaten either raw or cooked and is found in cuisines all across the world, from Europe to India.

It looks like a root vegetable, but actually grows above ground and is a member of the brassica family, along with cauliflower, kale, and broccoli. Kohlrabi consists of a hearty bulb, long stems, and large leaves.

Both the bulb and the leaves are edible. Kohlrabi leaves may be prepared and eaten much in the same way as kale or any other hearty greens. They can be sauteed, or added to salads.

I love kohlrabi because it's incredibly versatile. The bulb can be boiled, grilled, roasted, or sauteed and used to make everything from coleslaw to soups to casseroles.

It's an inexpensive vegetable that is usually found during the late summer and early autumn months and can be found in the produce section of your local grocery store or food coop or a farmer's markets.

Does Kohlrabi Need To Be Peeled?

Technically, the skin of a kohlrabi bulb is edible, but it's quite tough, so I recommend peeling it before cooking.

It may seem complicated, but the process of peeling kohlrabi is quite simple and much like that of peeling a butternut squash or any hearty, bulbous fruit or vegetable.

How To Peel Kohlrabi

This recipe calls for 25 oz. (roughly 1 ½ pounds) of sliced kohlrabi. The amount of kohlrabi used will vary depending on the size of the kohlrabi itself. I find that the best way to measure the sliced kohlrabi is to use a kitchen scale.

I recommend using small-medium sized kohlrabi bulbs, which are more tender and have a slightly sweeter flavor. Large bulbs of kohlrabi can be tough and have a slightly more bitter taste.

The key to cutting a vegetable like kohlrabi is to make sure that there is always a flat surface touching the cutting board. This prevents the kohlrabi from rolling around on the board, which makes the process safer.

1. The first step is to remove all of the stems and leaves from each kohlrabi bulb. The leaves may be used in another recipe (such as these Sautéed Kohlrabi Greens), or discarded in the compost bin or trash.
2. Pull any fibrous shoots from the surface of the kohlrabi bulbs off with your fingers and discard.
3. Cut the top and bottom of the kohlrabi off with a knife, creating a flat surface on both the top and bottom.
4. Placing one of the flat surfaces on a cutting board, remove the outer skin of the kohlrabi, cutting from the top to the bottom with the knife. Discard the tough outer skins.
5. Continue this process with the rest of the kohlrabi.

How To Slice Kohlrabi

To make this Kohlrabi Gratin, the kohlrabi must be thinly sliced after it has been peeled and all of the leaves and stems removed.

This process works much the same as if you were slicing potatoes for au gratin potatoes. In order for the kohlrabi to cook thoroughly, it must be sliced thinly. The best way to do this is to use a mandoline slicer.

A mandoline slicer is a kitchen gadget with a sharp blade that chops vegetables evenly and the thickness can be easily adjusted. I recommend setting the mandoline slicer to the thinnest setting when slicing kohlrabi for gratin.

If you do opt for a mandoline slicer, be sure to use the protective guard, so that you do not cut yourself. The blades of a mandoline slicer are VERY sharp and it's best to exercise caution.

If you don't have a mandoline slicer, feel free to slice the kohlrabi using the slicing blade of a food processor.

If using a large kohlrabi, it may need to be cut into halves or quarters in order to fit into the slicer.

Ingredients For Kohlrabi Gratin

Here's what you'll need to make it.

• 25 oz. Sliced Kohlrabi (or 1 ½ lbs.) (equals 10-15 small-medium kohlrabi)
• 6 cloves Garlic
• 1 Onion (white or yellow)
• 1 Tbsp. Olive Oil
• 6 Tbsp. Unsalted Butter (split)
• ¼ cup Gluten Free Flour Blend (or AP flour if not gluten free)
• 1 Tbsp. Dijon Mustard
• 1 ½ tsp. Kosher Salt (split)
• ¾ tsp. Pepper (split)
• 1 ½ cups Whole Milk
• ½ cup Heavy Whipping Cream
• 6 oz. Gruyere Cheese (grated)
• 1 ½ cups Gluten Free Panko Breadcrumbs (or regular Panko breadcrumbs if not gluten free)
• ¼ tsp. Garlic Powder
• ¼ tsp. Onion Powder
• ¼ tsp. Paprika
• 1 Lemon (zest only)
• Fresh Chives, Parsley or herbs of choice for garnish

What Is Gratin?

Gratin (or au gratin) is a dish made with layered vegetables that are topped with cream, cheese, and breadcrumbs and then baked in a shallow dish until the top is golden brown.

Gratin recipes are often made using potatoes, but technically can be prepared using any vegetables. A gratin can be made with cauliflower, Brussels sprouts, zucchini squash, turnips, or fennel.

This kohlrabi gratin is made using a 10 inch cast iron skillet, but any shallow, oven-safe dish should work fine. It can be cooked in an oval casserole dish as well.

The process of making kohlrabi gratin is much like that of any gratin or au gratin recipe.

The kohlrabi is sliced thinly and then layered in a shallow cooking dish along with minced garlic and onions, topped with a creamy cheese mixture, and finished with a breadcrumb topping.

The process of making gratin from scratch is a bit labor-intensive, but well worth the effort.

How To Make Gruyere Cheese Sauce

A gratin is just not a gratin without the addition of a creamy, decadent cheese sauce.

This recipe is made with Gruyere cheese, which is a hard Swiss cheese with a nutty texture that melts nicely. Gruyere is easily found in the cheese section of your local grocery store.

The cheese sauce provides this dish with a rich flavor that complements the flavor of the kohlrabi. It gives this gratin a nice, salty kick that keeps you coming back for more.

Making your own cheese sauce is easy to do and better than any pre-packaged cheese products out there.

1. To make it, simply cut the rind from a 6 oz. block of Gruyere cheese (or any sharp-flavored melting cheese). Grate the cheese using a cheese grater.
2. Place a sauce pan on the stove top and heat it to medium-low. Add 4 Tbsp. of unsalted butter to the pan and allow it to melt completely.
3. Add ¼ cup gluten free flour blend (or AP flour if not gluten free) to the butter and stir until completely combined with a whisk, creating a roux.
4. Cook the butter and flour mixture for a minute, and then slowly add 1 ½ cups of whole milk, stirring often to prevent it from sticking or burning.
5. Add ½ cup heavy whipping cream, stirring often.
6. Once the mixture is somewhat thick and creamy (this may take a few minutes), add 1 Tbsp. Dijon mustard, 1 ¼ tsp. kosher salt, and ½ tsp. pepper to the pan. Stir until combined.
7. Add the grated Gruyere cheese and stir until completely combined.
8. Continue to cook until the mixture is smooth, thick, and creamy.

How To Thicken Cheese Sauce

The process of making cheese sauce is much like that of making gravy. It requires a bit of patience to allow the sauce to come together smoothly.

Here are some tips to help ensure that the cheese sauce comes out thick and creamy and a few modifications that can be made to suit your tastes:

• You can use any variety of sharp, melting cheese (or combo of cheeses) that you like. I love Gruyere because of its sharp, nutty flavor, but you can choose sharp cheddar, white cheddar, Jarlsberg, Emmentaler, or Swiss cheese.
• It's best to choose a variety of cheese that melts quickly and will give your dish flavor (mild cheeses like mozzarella or Jack melt well, but lack in flavor).
• Use whole milk so that the cheese sauce has a high enough fat content. This will prevent the cheese sauce from becoming watery.
• Make sure to cook the cheese sauce over low heat so that it doesn't burn and to stir it often to prevent it from clumping together.
• If the cheese sauce seems too thin, simply continue to cook for a few more minutes until it reduces and thickens up.
• This recipe is gluten free and calls for a gluten free flour blend, but can be made using regular AP flour if gluten is not an issue for you.

How To Make The Breadcrumb Topping

It's super easy to whip up this breadcrumb topping and provides the dish with lots of extra savory flavor and an irresistible crunch.

This recipe is gluten free and calls for gluten free Panko breadcrumbs, but feel free to use regular Panko breadcrumbs if gluten is not an issue for you.

1. To make the breadcrumb topping, add 1 /2 cups of gluten free Panko breadcrumbs (or regular Panko breadcrumbs if not gluten free) to a bowl along with ¼ tsp. each of kosher salt and pepper, garlic powder, onion powder, and paprika.
2. Mix all of these ingredients until combined.
3. Melt 2 Tbsp. of unsalted butter in the microwave. Slowly pour the melted butter into the breadcrumb mixture and stir until completely combined.
4. Using a Microplane zester, add the zest of 1 lemon to the breadcrumb mixture and stir until combined.

How To Make Kohlrabi Gratin

A gratin is made by layering all of the components in a shallow dish and then baking it in the oven until the vegetables are tender and the cheese sauce hot and bubbly.

1. Heat the oven to 400 degrees Fahrenheit.
2. Mince 6 cloves of garlic and 1 onion (I recommend using a yellow or white onion).
3. Remove the leaves and stems, peel, and thinly slice 25 oz. (or 1 ½ pounds) of kohlrabi (see instructions above).
4. Prepare the cheese sauce (see instructions above).
5. Pour 1 Tbsp. of olive oil into a 10 inch cast iron skillet (or any oven-safe, shallow baking dish of similar size) and spread evenly across the bottom (this will prevent the kohlrabi from sticking to the bottom as it bakes).
6. Spread half of the minced garlic and onions evenly across the bottom of the skillet.
7. Layer half of the sliced kohlrabi evenly in the skillet.
8. Pour half of the cheese sauce evenly over the kohlrabi slices.
9. Spread the remainder of the minced garlic and onions over the cheese sauce.
10. Layer the remainder of the sliced kohlrabi over the top.
11. Pour the rest of the cheese sauce over the kohlrabi, making sure that it completely covers the vegetables.
12. Spread the breadcrumb mixture evenly over the top of the gratin.

How Long Does Gratin Take To Bake?

Once the gratin is assembled, it's time to cover it with foil and bake in the oven.

Cooking times may vary, but in general it takes a little more than an hour for this gratin to bake. There is a lot of kohlrabi in this gratin and it is a slightly tough vegetable, which means it takes some time to cook through properly.

The gratin bakes for one hour covered tightly with foil. This helps to prevent the breadcrumb topping from burning. The foil is then removed and the gratin bakes for another 10 minutes or so, which helps the breadcrumb topping to become golden brown and crispy.

1. Once assembled, cover the gratin tightly with foil and place in an oven that has been heated to 400 degrees. Bake for 60 minutes.
2. After 60 minutes, remove the tinfoil and return the skillet to the oven for another 10 minutes.
3. Remove the skillet from the oven and allow to cool for 5-10 minutes before serving.
4. Garnish the gratin with some minced chives, parsley, or herbs of choice. This helps to add some color and fresh flavor to the dish.

The gratin is finished cooking when the kohlrabi is tender, but not mushy and easily pierced with a knife or fork.

What To Serve With Kohlrabi Gratin

This dish makes for a great holiday side dish. It's perfect served alongside some roasted turkey, ham, or beef with your favorite sides during the holidays or dinner party.

It's great with either buttermilk mashed potatoes or savory sweet potatoes for Thanksgiving or Christmas dinner. Gratin also pairs nicely with green bean casserole, Brussels sprouts, or this savory fennel stuffing.

The rich flavor of the Gruyere cheese sauce pairs nicely with air fryer parsnips, harvest butternut squash salad, or roasted pumpkin salad.

It would also taste great with some roasted vegetables like asparagus or any roasted or grilled meats like these Italian short ribs or pot roast, grilled chuck steak or Steak Diane.

Can This Gratin Be Made Ahead Of Time?

Yes!

The holidays are a busy time and it's nice to be able to prepare some dishes ahead of time.

• To make ahead, simply assemble to recipe as instructed (without the breadcrumb topping), without baking. Cover the unbaked dish tightly with plastic wrap and store it in the refrigerator for a day before baking.
• Prepare the breadcrumb topping just before baking.
• To bake, remove the plastic wrap, add the breadcrumb topping, cover tightly with foil, and bake as directed. Add the fresh herbs right before serving.

How Long Does It Last In The Fridge?

Any leftovers should last 2-3 days stored in an airtight container in the fridge.

Make sure to allow the gratin to cool completely before transferring to the fridge for storage.

Can It Be Frozen?

For optimal taste and texture, I do not recommend freezing this gratin.

If you love this recipe, be sure to check out these Au Gratin Potatoes!

Love kohlrabi? Check out these recipes!

• Kohlrabi Schnitzel
• Mashed Kohlrabi
• Kohlrabi Slaw

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Sweet Potato Casserole