Preheat your oven to 350°F.

In a large skillet over medium heat, cook the ground beef until browned. Drain excess fat.

Add the chopped onion and minced garlic to the skillet and sauté until the onion is translucent, about 5 minutes.

Stir in the cream of mushroom soup, cream of chicken soup, sour cream, salt, and black pepper. Mix until well combined.

In a greased 9x13-inch baking dish, spread the beef mixture evenly across the bottom.

Layer the frozen tater tots on top of the beef mixture in a single, even layer.

Sprinkle the shredded cheddar cheese evenly over the tater tots.

Bake in the preheated oven for 30 minutes.

Remove from the oven and sprinkle the mozzarella cheese on top. Return to the oven and bake for an additional 10-15 minutes, or until the cheese is bubbly and golden brown.

Let it cool for a few minutes before serving.