Heat the oven to 375°F. Lightly grease 8 cups of a standard muffin tin.
In a large bowl, combine the ground turkey, egg, breadcrumbs, chopped onion, 2 tablespoons of the BBQ sauce, garlic powder, smoked paprika, salt, and black pepper. Mix gently until just combined.
Divide the mixture among the 8 prepared muffin cups. Shape each portion into a rounded top, then brush the remaining BBQ sauce over the muffins.
Bake for 20 to 25 minutes, until the centers reach 165°F. Let the muffins rest in the tin for 5 minutes before removing them.
While the muffins bake, cook the elbow macaroni according to the package directions. Drain it and set it aside.
Melt the butter in a saucepan over medium heat. Whisk in the flour and cook for about 1 minute, stirring constantly. Gradually whisk in the milk and cook until the sauce thickens, about 3 to 5 minutes.
Remove the saucepan from the heat. Stir in the shredded cheddar until melted, then fold in the cooked macaroni. Serve the mac and cheese alongside the BBQ turkey meatloaf muffins.