Preheat oven to 375°F
Brown 1 lb ground beef in a skillet
Drain excess grease
Add 1 diced onion if desired
Stir in 1 can cream of mushroom soup
Stir in 1/2 cup milk
Add salt and pepper to taste
Mix in 1 to 2 cups frozen mixed vegetables if desired
Spread the beef mixture into a greased 9×13-inch baking dish
Arrange tater tots in a single layer on top
Sprinkle shredded cheddar cheese over the tater tots if desired
Bake for 35 to 45 minutes until hot and bubbly
Bake a few extra minutes for extra crispy tater tots
Let rest for 5 minutes before serving