My Cauliflower and Broccoli Gratin was inspired by a dinner that I attended a few months ago here in Chicago. They had this as a side option, and we all know you can’t go wrong with creamy, cheesy vegetables. One bite, and I immediately fell in love! This is definitely one recipe that will be sure to wow your friends and family at the dinner table!
Preheat the oven to 400°F. Take a 9-by-13 inch casserole dish and coat it with 1 tbsp. of butter.
In a large pot, heat 1 tbsp. of butter over medium heat. Add the chopped onion, and cook until the onion is translucent (4 to 5 minutes). Add the garlic and cook an additional minute.
Melt the remaining 2 tablespoons of butter in the pot. Stir in the flour to combine. Cook for about 2 to 3 minutes, stirring occasionally, until the mixture is just starting to turn golden.
Using a whisk, gradually add the milk first, followed by the heavy cream. Bring mixture to a simmer (NOT BOIL), whisking for about 6-7 minutes, or until the sauce has thickened enough to coat a spoon.
In a separate large pot, bring 2 cups of water to a boil. Cook the broccoli and cauliflower until they just begin to soften( about 5 minutes). Drain and pour into the sauce mixture.
Season the mixture with the nutmeg, salt and pepper. Toss well to make sure the vegetables are fully coated. Pour the vegetable and sauce mixture into the casserole dish. Sprinkle all of the cheeses evenly over the surface.
Bake until the sauce is bubbly and the cheese has melted, about 40 minutes. Let it sit for about 5-10 minutes prior to serving.