Brown ground beef with onion, salt and pepper. drain. Mix cream soup and milk in a bowl and stir well. Add more salt and pepper if desired. Add browned meat to soup mixture, stir. Add veggies and mix well.
Preheat oven to 350. Spray a 9x13 pan with cooking spray. Pour meat and soup mixture into pan. Top with cheese, then place tater tots on top of cheese, then add more cheese. Bake in oven for 30 min.