Preheat your oven to 375°F and let it reach full temperature. Grease a 9x13 inch casserole dish with cooking spray or butter.

Heat a large skillet over medium heat without adding oil. Add the ground beef and immediately break it into small crumbles. Add the diced onions and cook for 5-7 minutes until the beef shows no pink and the onions become soft and translucent. Season with salt, pepper, and optional spices. Drain excess fat thoroughly by tilting the pan and using paper towels.

Reduce heat to low and stir in the cream of mushroom soup and sour cream, mixing until completely smooth with no lumps. Cook for 2-3 minutes until heated through and well-combined. The mixture should be thick and creamy.

Pour the beef mixture into the prepared casserole dish and spread it evenly across the bottom using a spatula. Sprinkle 1 cup of shredded cheddar cheese over the beef mixture in an even layer.

Arrange the frozen tater tots in a single layer on top of the cheese, leaving tiny gaps between each tot without overlapping. Place on the center oven rack and bake for 25-30 minutes until the tots turn deep golden brown. Rotate the dish halfway through for even browning.

Remove from the oven and immediately sprinkle the remaining 1 cup of cheese over the hot tater tots. Return to the oven for 5 minutes until the cheese melts completely and becomes bubbly. Let rest for 5 minutes before serving to help the layers set.