Preheat the Oven: Preheat your oven to 375°F (190°C) and grease a 9x13-inch baking dish.
Cook the Beef: In a large skillet, cook ground beef over medium heat until browned. Add diced onion and garlic, and sauté until softened. Stir in paprika, onion powder, salt, and pepper. Drain excess fat.
Mix the Sauce: In a mixing bowl, combine sour cream, cream cheese, and cream of mushroom soup. Stir until smooth.
Combine Ingredients: In a large bowl, mix the cooked pasta, ground beef mixture, and the creamy sauce. Stir in 1 cup of shredded cheese.
Assemble the Casserole: Transfer the mixture to the prepared baking dish, spreading it evenly. Sprinkle the remaining cheese over the top.
Bake: Cover the dish with foil and bake for 20 minutes. Remove the foil and bake for an additional 10-15 minutes, or until the cheese is melted and bubbly.
Garnish and Serve: Sprinkle with chopped parsley (if using) and serve warm.