Preheat Your Oven: Start by preheating your oven to 350°F (175°C).
Sauté the Vegetables: In a large skillet, melt the butter over medium heat. Add the chopped onions and minced garlic, sauté until the onions are softened.
Cook the Mushrooms: Add the sliced mushrooms to the skillet and cook until they are tender.
Prepare the Sauce: Sprinkle the flour over the sautéed vegetables and cook for about a minute. Gradually whisk in the chicken broth and cream, keeping it on medium heat until the sauce thickens (about 5 minutes).
Combine Ingredients: Stir in the shredded turkey, cooked pasta, peas, salt, pepper, and paprika. Mix well to combine all ingredients.
Transfer to Casserole Dish: Pour the mixture into a greased casserole dish.
Add Toppings: Top with freshly grated Parmesan cheese and breadcrumbs if you’re using them.
Bake: Bake the casserole for 25-30 minutes until it’s bubbly and golden on top.
Garnish and Serve: Remove from the oven, garnish with chopped parsley, and serve warm.