Start by turning on your oven to preheat at 400 degrees Fahrenheit. Lightly coat a medium baking dish or casserole dish with oil or butter.
Add the ground beef to a large skillet set over medium heat and cook along the diced onion until perfectly browned and the onion softens; for about 5 to 7 minutes. Get rid of any excess fat if desired.
Add in the marinara sauce (or pizza sauce), Italian seasoning, and a light pinch of salt and pepper. Combine the ingredients and let them simmer for a few minutes.
Spread an even layer of the cooked beef and sauce mixture in the greased baking dish, then Scatter 1 cup of shredded cheese on top.
Add in the tater tots on top to form a single layer, then sprinkle the rest of the shredded cheese on top.
Place the baking dish in the oven and let it cook for 25 to 30 minutes; until the tater tots become crispy and golden and the cheese melted.
Top your baking dish with any toppings you prefer like pepperoni or black olives. Place back the baking dish in the oven to cook for an additional 5 minutes to heat the toppings.
Get the casserole out of the oven and let it cool for a while. Savor every bite of your pizza flavored casserole!