Preheat the oven to 375°F (190°C).
In a large skillet, brown the ground beef over medium heat until cooked through, about 5-7 minutes.
Add diced onions and minced garlic to the skillet, cooking until the onions are translucent, about 5 minutes.
Stir in the cream of mushroom soup and season with salt and pepper. Mix until well combined.
If using, stir in the mixed vegetables. Cook for an additional 2-3 minutes to warm through.
Transfer the beef mixture to a greased 9x13-inch casserole dish, spreading it evenly.
Top with shredded cheddar cheese, ensuring an even layer over the beef mixture.
Arrange the frozen tater tots neatly over the cheese layer, covering the entire surface.
Bake in the preheated oven for 30-35 minutes, or until the tots are golden brown and crispy.
Remove from the oven and let it cool for a few minutes before serving.