Preheat oven to 400°F and line a baking sheet with parchment.
Bake tater tots for 15–20 minutes until golden and crisp, flipping halfway.
Cook ground beef with onion, salt, and pepper until browned, about 6–8 minutes. Stir in ketchup and mustard.
Let tots cool slightly. Press them firmly into muffin tin cups to form cone shapes. Bake 10 more minutes to set.
Mix cooked beef with crumbled bacon, cheddar, and mozzarella cheese.
Spoon the cheeseburger mixture into tot cones, pressing gently. Top with extra cheese or bacon if desired.
Bake cones for 5 minutes until cheese is bubbly and melted.
Remove cones carefully from muffin tin and serve hot with toppings.
