Preheat your oven to 375°F (190°C).
In a large skillet, brown the ground beef over medium heat, breaking it apart.
Add the chopped onions and cook until softened, about 3-5 minutes.
Stir in the ketchup, Worcestershire sauce, mustard, garlic powder, pepper, and cook for an additional 2-3 minutes until heated through.
Spread the beef mixture evenly in a greased baking dish.
Arrange the tater tots in a single layer over the beef mixture.
Sprinkle the shredded cheddar cheese evenly over the tater tots.
Bake for 30-35 minutes, or until tater tots are golden brown.
Let cool for 5-10 minutes before serving.