Preheat your oven to 375°F.
Bring a large pot of salted water to a boil. Cook the pasta according to package directions until just al dente. Drain and set aside.
In a big skillet, cook the ground beef over medium heat until no longer pink. Drain any extra grease.
Stir in the pizza sauce, marinara sauce, garlic powder, salt, and pepper. Let it bubble gently for a few minutes.
Add the cooked pasta to the skillet and stir until everything’s cozy and well combined.
Toss in half of the pepperoni, half the mozzarella, and all the Parmesan cheese. Stir again.
Scoop everything into a greased 9x13-inch baking dish. Sprinkle the remaining mozzarella on top, then decorate with the rest of the pepperoni and the diced bell pepper.
Bake uncovered for 20-25 minutes until golden, bubbly, and impossible to resist.
Garnish with fresh basil if you’re feeling fancy. Serve hot!