Preheat the oven to 375°F (190°C).
In a large skillet over medium heat, cook the ground beef, breaking it up as it browns (about 5–7 minutes).
Add the diced onion and minced garlic, and cook for another 2–3 minutes until softened.
Stir in the cream of mushroom soup and frozen mixed vegetables.
Add salt and pepper to taste.
Let the mixture cook for a few more minutes until everything is heated through.
Transfer the beef and vegetable mixture into a 9x13-inch baking dish.
Sprinkle shredded cheddar cheese evenly over the top.
Arrange the frozen tater tots in a single layer over the cheese, covering the entire casserole.
Bake for 30–35 minutes, or until the tater tots are golden brown and crispy.
If the cheese is not fully melted, bake for an additional 5 minutes.
Let the casserole cool for a few minutes before serving. Enjoy!