Cheesy Mushroom and Broccoli Casserole

INGREDIENTS

• 3 tablespoons butter, plus extra for casserole dish
• 1/2 pound shiitake or baby bella mushrooms, sliced
• Special equipment: 1 1/8-quart oval casserole dish
• 1/4 cup onions, chopped
• 1 1/2 cups heavy cream
• Salt and freshly ground black pepper
• 1/2 cup chicken stock
• 1/2 teaspoon cayenne pepper
• 3 cups cooked rice
• 2 cups shredded Cheddar-Monterey blend
• 2 cloves garlic, finely chopped
• 1 (10-ounce) box frozen chopped broccoli, thawed and drained
• 2 tablespoons all-purpose flour
• 1/2 teaspoon garlic powder