Cook the Beef: In a large skillet, cook the ground beef over medium heat until browned. Add the diced onion and garlic, cooking until softened. Drain any excess fat.
Mix the Ingredients: In a large bowl, combine the cooked beef mixture, cream of mushroom soup, cream of chicken soup, sour cream, and 1 cup of shredded cheddar cheese. Mix until well combined. Season with salt and pepper to taste.
Assemble the Casserole: Spread the beef mixture evenly in a 9×13 inch baking dish. Top with an even layer of frozen tater tots.
Bake: Bake in the preheated oven for 35-40 minutes, or until the tater tots are golden brown and crispy.
Add Cheese: Sprinkle the remaining 1 cup of shredded cheddar cheese over the top of the casserole. Return to the oven and bake for an additional 5-10 minutes, or until the cheese is melted and bubbly.
Serve: Let the casserole cool for a few minutes before serving.
