Preheat oven to 375°F (190°C) and grease a baking dish.
In a skillet cook ground beef and diced onion until browned.
Drain excess grease and season with garlic powder, salt, and black pepper.
In a bowl mix cream of mushroom soup and milk until smooth.
Combine the soup mixture with the cooked beef.
Spread the mixture evenly into the prepared baking dish.
Sprinkle shredded cheddar cheese over the beef mixture.
Arrange frozen tater tots evenly on top.
Bake for 35–40 minutes until the tater tots are golden and crispy.