Preheat your oven to 375°F (190°C).

In a large skillet over medium heat, cook the ground beef and diced onion until the beef is browned and the onion is translucent, about 5-7 minutes. Drain any excess fat.

Stir in the garlic powder, Italian seasoning, salt, and black pepper. Add the pizza sauce and mix well. Remove from heat.

In a greased 9x13-inch baking dish, spread the beef mixture evenly across the bottom.

Layer the frozen tater tots over the beef mixture, arranging them in a single layer.

Sprinkle the shredded mozzarella cheese evenly over the tater tots, followed by the sliced pepperoni and grated Parmesan cheese.

Bake in the preheated oven for 30-35 minutes, or until the tater tots are golden brown and the cheese is bubbly.

Remove from the oven and let it cool for 5 minutes before serving. Garnish with fresh basil leaves if desired.