Preheat oven to 350°F and grease a 9x13-inch baking dish.
In a large skillet over medium-high heat, brown the ground beef with diced onion until meat is fully cooked and onion is softened, about 8 minutes. Drain excess fat.
In a large bowl, combine the cooked pasta, browned beef mixture, crumbled bacon, cheese soup, sour cream, 1 1/2 cups cheddar cheese, American cheese, garlic powder, salt, and pepper. Mix until well combined.
Pour the mixture into the prepared baking dish and spread evenly.
Top with remaining 1/2 cup cheddar cheese and sprinkle crushed crackers over the top.
Bake for 30-35 minutes until bubbly and golden brown on top.
Let stand for 5 minutes before serving.