Preheat your oven to 200°C (390°F).

Cook the Penne pasta according to package instructions until it’s al dente. Drain the pasta and set aside.

While the pasta is cooking, heat olive oil in a large pan over medium heat. Add the garlic and onions, sauté until they become fragrant and the onions are translucent.

Add the zucchini and bell peppers to the pan. Season with salt and pepper. Sauté the vegetables until they are slightly tender.

Combine the cooked pasta, sautéed vegetables, and marinara sauce in a large mixing bowl. Stir until everything is evenly coated with the sauce.

Transfer the pasta and vegetable mixture into a baking dish. Top it with shredded mozzarella cheese.

Bake in the preheated oven for 20-25 minutes or until the cheese is melted and slightly golden.

Allow the pasta bake to cool for a few minutes before serving. Garnish with fresh basil leaves before serving.