Stir the mushroom soup and milk in a small bowl until the mixture is smooth.
Cook the beef, onion and chili powder in a 3-quart saucepan over medium-high heat until the beef is well browned, stirring often to separate meat. Pour off any fat.
Stir the tomato soup in the saucepan and cook until the mixture is hot and bubbling.
Layer half the beef mixture, 2 lasagna noodles and half the mushroom soup mixture in an 8-inch square baking dish, trimming the noodles to fit the dish, if needed. Repeat the layers. Sprinkle with the cheese.
Bake at 400 degrees F. for 30 minutes or until the filling is hot and the cheese is melted. Let stand for 10 minutes before serving.