Cheesy Cauliflower and Broccoli Casserole

3 tablespoons butter
1 1/2 lbs total of broccoli and cauliflower (or any combination of veggies that you like), steamed until tender
2 cloves garlic, minced
1/2 teaspoon cayenne pepper
1/2 cup chicken (or veggie) stock
2 cups shredded cheese (Cheddar or Monterrey Jack blend)
Salt and pepper to taste
2 tablespoons flour
1/4 cup onions, chopped
1/2 teaspoon garlic powder
1 1/2 cups heavy cream
3 cups cooked rice

Oven at 425.
Grease a 1 1/2 quart casserole dish. In a large pot, melt the butter. Cook onions, garlic, garlic powder, cayenne. Cook until onion is golden. Add flour and cook one minute. Add heavy cream and chicken stock. Cook until mixture starts to thicken, stirring to avoid lumps. Once thickened, take off heat and add one cup of the cheese to make a sauce. Combine sauce with rice and veggies and put in casserole dish. Top with remaining cheese. Bake about 20 minutes, until cheese is golden.