Step 1: Preheat your oven to 375°F (190°C). Lightly grease a 9×13 inch baking dish.
Step 2: In a large skillet or Dutch oven, heat 1 tbsp of olive oil over medium-high heat. Add the ground beef and chopped onion. Cook, breaking up the beef with a spoon, until the beef is fully browned and the onion is softened, about 7-10 minutes. Drain any excess grease thoroughly.
Step 3: Stir in the garlic powder, salt, and black pepper. Cook for another minute, allowing the spices to become fragrant.
Step 4: Remove the skillet from the heat. Stir in the condensed cream of mushroom soup, cream of chicken soup, and milk until well combined and smooth. Then, fold in 1 cup of shredded cheddar cheese.
Step 5: Spread the beef and soup mixture evenly into the prepared baking dish.
Step 6: Arrange the frozen tater tots in a single, even layer over the beef mixture.
Step 7: Bake for 30 minutes. At this point, the tater tots should be starting to turn golden brown. Remove the casserole from the oven and sprinkle the remaining 1/2 cup of shredded cheddar cheese over the tater tots.
Step 8: Return the casserole to the oven and continue baking for another 10-15 minutes, or until the cheese is melted and bubbly and the tater tots are golden brown and crispy.
Step 9: Remove from oven and let stand for 5-10 minutes before serving.