Buffalo Turkey Meatloaf

Preheat oven to 350 degrees F (175 degrees C). Line a 9x13-inch baking pan with aluminum foil; spray lightly with cooking spray. Combine ground turkey, grated onion, salt, and black pepper in a large bowl; mix to combine. Transfer turkey mixture to baking pan and shape into a loaf. Bake meatloaf in the preheated oven until light golden, about 40 minutes. Melt butter in a small saucepan over low heat. Stir in hot pepper sauce, 1 teaspoon garlic powder, and 1 teaspoon onion powder. Pour evenly over meatloaf. Return meatloaf to the oven and cook until flavors are absorbed, about 5 minutes more. An instant-read thermometer inserted into the center should read at least 165 degrees F (74 degrees C). Combine sour cream, mayonnaise, and blue cheese crumbs in a bowl to make blue cheese dressing. Season with 1/2 teaspoon garlic powder, 1/2 teaspoon onion powder, and black pepper. Serve alongside meatloaf.