Begin by preheating your oven to 375°F (190°C) to ensure it's hot enough for baking.
Cook the penne pasta in a large pot of salted boiling water according to the package instructions, aiming for an al dente texture. Once cooked, drain the pasta and set it aside.
In a spacious mixing bowl, combine the drained penne pasta with the marinara sauce. Add in half of the shredded mozzarella cheese, the pepperoni slices, diced green bell pepper, sliced black olives, diced red onion, Italian seasoning, garlic powder, and a sprinkle of salt and pepper. Stir thoroughly until all ingredients are well combined, ensuring the pasta is coated in sauce and cheese.
Carefully transfer the pasta mixture into a greased 9x13 inch baking dish, spreading it evenly across the bottom.
Sprinkle the remaining mozzarella cheese generously over the top of the pasta mixture, creating a luscious cheesy layer.
Place the baking dish in the preheated oven and bake for approximately 25-30 minutes, or until the cheese is bubbly and has formed a beautiful golden crust.
Upon removing the dish from the oven, allow it to cool for a few minutes to let the flavors meld. Before serving, garnish with fresh basil leaves for a touch of vibrant color and freshness.
Serve your warm and delicious cheesy pizza pasta bake directly from the oven and enjoy this comforting meal!