Trim (but do not remove entirely) the bottom of the Brussels sprouts (if they are dry and brown) and remove any of the damaged or wilted outer leaves and discard. Cut the sprouts in half lengthwise.
Chop the mid-sized Brussels sprouts in half and larger ones into quarters, so that they are relatively even in size to ensure even cooking.
Arrange the chopped Brussels sprouts on a large baking sheet and drizzle them with 2 Tbsp. olive oil. Sprinkle ¼ tsp. each kosher salt and pepper over the sprouts and toss until completely coated in the oil and spices.
Place the baking sheet in the oven and roast the Brussels sprouts for 15 minutes.