Turn on your oven and set at 375 degrees Fahrenheit to preheat.
Add the ground beef to a medium skillet set over medium heat and stir until browned. Add in the diced onions and cook to soften. Sprinkle some salt, pepper and any additional spices you prefer like paprika, garlic powder or chili powder. Remove any excess fat if desired.
Mix in the cream of mushroom soup and the sour cream until well combined with the ground beef. Let everything cook for another 2 to 3 minutes until heated through.
Lightly grease a casserole dish with oil or butter then spread the cooked beef mixture to form an even bottom layer. Top the beef layer with 1 cup of shredded cheddar cheese well spread to cover the bottom layer. Arrange the frozen tater tots forming an even top layer.
Place the casserole dish in the oven and cook for about 25 to 30 minutes; until the tater tots become golden and crispy.
Get the casserole dish out of the oven and top with the remaining shredded cheddar cheese to form a final layer. Place the dish back in the oven to cook for another 5 minutes, until the cheese is gooey and bubbly.
Allow the casserole to cool for couple minutes then serve it family style or divide portions on individual plates. Garnish with bacon bits, chopped green onion or chopped parsley. Enjoy!