Preheat your oven to 375°F (190°C). Grease a 9x13-inch baking dish with non-stick cooking spray.
In a large skillet over medium heat, cook the ground beef until it's no longer pink, breaking it up with a spoon as it cooks. Drain any excess fat.
Add the minced garlic and diced onion to the skillet with the cooked beef. Cook for an additional 2-3 minutes until the onion is soft and translucent.
Spread the cooked beef mixture evenly in the bottom of the prepared baking dish.
Sprinkle half of the shredded cheddar cheese over the beef layer.
Next, arrange the frozen tater tots in a single layer over the cheese.
In a small bowl, mix together the sour cream, garlic powder, salt, and pepper. Spread this mixture evenly over the tater tots.
Sprinkle the remaining shredded cheddar cheese over the top.
Cover the baking dish with aluminum foil and bake in the preheated oven for 30 minutes.
Remove the foil and bake for an additional 10-15 minutes, or until the cheese is melted and bubbly, and the tater tots are golden brown.
Let the casserole cool for a few minutes before serving. Enjoy!