Creamy, cheesy, healthy, low-carb, and secretly easy to make - this Cauliflower au Gratin will put your other casserole recipes to shame! Cauliflower florets are roasted in the oven, tossed in a creamy Gruyere cheese sauce, topped with Parmesan cheese, and then baked until golden and crispy. You can serve this vegetarian and keto-friendly side dish for a fancy Thanksgiving or holiday dinner, or meal prep it for busy weeks!
Preheat oven to 425°F.
Add cauliflower florets to a 13 by 9-inch baking dish along with 2 tablespoons of oil, ½ teaspoon salt, and ¼ teaspoon black pepper.
Reduce oven temperature to 400 °F and return cauliflower dish to oven for 20-25 minutes.
For an extra crispy topping, broil casserole for 2-3 minutes under a high broil.