Preheat the oven:
Preheat your oven to 350°F (175°C).

Cook the beef:
In a large skillet, brown the ground beef over medium heat, breaking it up as it cooks. Once the beef is cooked through, drain any excess fat and return it to the skillet.

Add the seasonings:
Add the diced onion to the beef and cook until softened, about 3-4 minutes. Season with salt, pepper, and any optional seasonings like garlic powder or paprika.

Mix in the soup and sour cream:
Stir in the cream of mushroom soup and sour cream until fully combined. Remove from heat.

Assemble the casserole:
Spread the beef mixture evenly in a 9×13-inch baking dish. Top with 1 cup of shredded cheddar cheese. Arrange the frozen tater tots in a single layer on top of the cheese.

Bake:
Bake the casserole in the preheated oven for 25-30 minutes, or until the tater tots are golden and crispy.

Add the remaining cheese:
Sprinkle the remaining 1 cup of shredded cheddar cheese over the casserole 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. Enjoy!