Preheat oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish.
In a large skillet, cook the ground beef and onion over medium heat until beef is browned. Drain excess fat.
Stir in the cream of mushroom soup, milk, corn, salt, and pepper. Mix well.
Spread the beef mixture evenly in the prepared baking dish.
Sprinkle 1 cup of cheddar cheese over the beef mixture.
Arrange frozen tater tots in a single layer on top.
Bake for 30-35 minutes or until tater tots are golden brown and crispy.
Sprinkle remaining cheddar cheese on top and bake for an additional 5 minutes, until melted.
Let cool slightly before serving. Enjoy!