Preheat your oven to 425°F (220°C).
In a large skillet over medium heat, cook the ground beef until browned. Drain excess fat.
Add the diced onion and bell pepper to the skillet and sauté until softened, about 5 minutes. Stir in garlic powder, Italian seasoning, salt, and pepper.
Pour in the pizza sauce and mix well. Remove from heat.
In a greased 9x13-inch baking dish, spread the beef and vegetable mixture evenly across the bottom.
Layer the frozen tater tots on top of the beef mixture in a single layer.
Sprinkle the shredded mozzarella cheese and sliced pepperoni over the tater tots.
Finish by sprinkling grated Parmesan cheese on top.
Bake in the preheated oven for 25-30 minutes, or until the tater tots are golden brown and crispy.
Let it cool for 5 minutes before serving.