Set a large skillet over medium heat and melt the butter. Cook the garlic for 30-45 seconds. Add the flour and cook for 1-2 minutes, stirring frequently, until lightly browned.
Whisk in milk and cream and bring to a simmer, Cook until slightly thickened, then stir in 1 cup of mozzarella and ½ cup of parmesan cheese. Season with salt and pepper to taste.
Spray your casserole dish with cooking spray, then add the pasta, broccoli, and chicken. Pour the cheese sauce overtop and stir to combine. Top with the remaining cheese.
Bake uncovered for 15-20 minutes until the cheese is melted and lightly browned.
This baked chicken and broccoli pasta is an easy, flavorful pasta casserole that is sure to be a family favorite.