Preheat the oven to 375.

Add the ground beef to a large skillet over medium heat. Cook, crumbling into small pieces, until browned and cooked through. Drain if necessary.

In a small pot over medium heat, melt the butter. Add the flour and stir to make a paste. Cook 2-3 minutes, until golden brown. Slowly whisk in the milk, stirring frequently, and cook until thickened. Remove from heat and stir in the salt and pepper.

Pour the cream sauce into the skillet with the ground beef and stir to combine. Add the frozen vegetables and stir until combined.

Pour the beef and vegetable mixture into a 9 x 9 baking dish. Sprinkle the cheddar cheese over the top. Layer the frozen tater tots over the top of the cheese, covering the entire surface.

Bake 50-55 minutes, until the tater tots are crisp and browned and the sauce is bubbling.