Creamy Broccoli and Rice with Cheese, Cheese, Cheese

Preheat oven to 375. In a large heavy bottomed skillet or dutch oven over medium heat, melt 3 tbsp of the butter with the onion and garlic, allow to cook for 5 minutes, then remove garlic and discard. Sprinkle flour over onions and butter, cook--whisking occasionally for two minutes. Slowly add the chicken broth and then the cream while continuously whisking. Bring to a boil and then remove from heat. Add one cup of the cheddar, all of the Monterey Jack and the Parmigiano, whisk until smooth. Add the rice, broccoli, salt, pepper and cayenne. Mix well. Transfer to a casserole dish prepared with the remaining 1 tbsp of butter and sprinkle top with remaining cheddar and mozzarella. Bake uncovered for 45-55 minutes. Allow to rest for at least 5 minutes before serving.