mushroom, cheese, and brocoli casserole

Ingredients

• 3 tablespoons butter, plus extra for casserole dish
• 2 tablespoons all-purpose flour
• 1 pound shiitake or baby bella mushrooms, sliced
• 1/4 cup chopped onion
• 1/2 teaspoon garlic powder
• 1/2 teaspoon cayenne pepper
• 1 1/2 cups heavy cream
• 1/2 cup chicken stock
• 1- 10 ounces frozen chopped brocoli
• 2 cups sharp cheddar cheese
• 3 cups cooked rice
• - salt/pepper
• 1/2 cup dry white wins