Creamy Turkey and Mushroom Casserole

Ingredients

• 16 ounces penne pasta
• 1 cup grated parmesan cheese
• 2 tablespoons chopped parsley
• 1 cup frozen peas
• 3 cups cooked turkey, diced
• 1 cup diced yellow onion
• 6 tablespoons unsalted butter, divided
• cooking spray
• 2 cups half and half
• 12 ounces button mushrooms, sliced
• 3 teaspoons minced garlic
• 1/4 cup all-purpose flour
• 1/2 cup Italian style breadcrumbs
• 1 1/2 cups low-sodium chicken broth