Heat oven to 400 degrees Fahrenheit.
Mince 2 cloves of garlic and ½ an onion (any color). You can also use 2 shallots in place of onion if you prefer.
Mince 1 bell pepper (any color).
Chop 1 packed cup of fresh spinach.
Shred 1 cup of Pepper Jack cheese (or cheese of choice).
Peel 2 sweet potatoes and cut them into chunks, making sure they are all relatively the same size to ensure even cooking.
Place the diced sweet potatoes onto a baking sheet. Drizzle them with 2 Tbsp. olive oil and sprinkle 2 tsp. each cumin and chili powder over the top, along with ¼ tsp. each kosher salt and pepper. Toss the sweet potatoes until completely coated in the oil and spices. Put the baking sheet in the oven and roast the sweet potatoes for 20 minutes. Once they are tender, but not mushy remove the baking sheet from the oven and set aside to cool.
Reduce the oven temperature to 375 degrees Fahrenheit.
Place a cast iron skillet on the stove top and heat to medium-high. Add 1 Tbsp. olive oil to the skillet. Once heated, add the minced garlic, onions, and bell peppers. Saute for 5-6 minutes, stirring often. Remove the skillet from the heat and set aside to cool.
Add the roasted sweet potatoes to the cast iron skillet and stir them into the sauteed veggies.
Crack 10 eggs into a bowl and add ⅓ cup heavy whipping cream, along with ¼ tsp. each kosher salt and pepper. Stir until completely combined. Add the shredded cheese and chopped spinach to the egg mixture. Stir until combined. Pour the egg mixture over the top of the sweet potato vegetable mixture in the cast iron skillet. Shake the skillet until the eggs have settled into the pan evenly.
Pop the cast iron skillet into the oven and bake for 24-25 minutes, or until the edges of the frittata are slightly golden brown and the center is no longer jiggly. Remove from the oven and allow to cool 5 minutes before serving.
To Serve: Run a knife along the edges of the frittata and cut it into slices. Serve with fresh cilantro, avocado, and salsa or toppings of choice (optional).