STEP 1: COOK THE PASTA

1. Boil Water: In a large pot, bring salted water to a boil. The salt enhances the pasta’s flavor as it cooks.
2. Cook the Pasta: Add the penne or rigatoni and cook until al dente, about 1-2 minutes less than the package instructions. This ensures the pasta retains some firmness and won’t become mushy when baked. Drain and set aside.

STEP 2: SAUTE THE VEGETABLES

1. Heat Olive Oil: In a large skillet, heat the olive oil over medium heat.
2. Cook Onions and Garlic: Add the chopped onion and minced garlic. Sauté for about 3-4 minutes until the onion becomes translucent, releasing its sweetness.
3. Add Bell Pepper and Mushrooms: Stir in the chopped bell pepper and sliced mushrooms. Cook for another 5 minutes until the vegetables are tender, adding depth to the flavor profile.
4. Incorporate Spinach: Add the chopped spinach and cook until wilted, about 2 minutes. Season with salt, pepper, and Italian seasoning for a harmonious blend of flavors.

STEP 3: MIX THE SAUCE

1. Combine Sauce and Vegetables: Pour in the marinara sauce and stir to combine with the sautéed vegetables. The sauce adds moisture and flavor to the dish.
2. Add Pasta: Gently fold in the cooked pasta until everything is well coated in the sauce. This ensures every bite is packed with flavor.

STEP 4: ASSEMBLE IN BAKING DISH

1. Prepare Baking Dish: Preheat your oven to 350°F (175°C). Grease a deep-dish baking dish or a 9×13-inch casserole dish to prevent sticking.
2. Layer the Pasta Mixture: Pour the pasta mixture into the prepared dish, spreading it evenly for even cooking.

STEP 5: ADD CHEESE AND TOPPINGS

1. Sprinkle with Cheese: Generously sprinkle the shredded mozzarella cheese over the top of the pasta. Don’t be shy with the cheese; it’s a key ingredient!
2. Add Pepperoni or Other Toppings: Layer the pepperoni slices evenly over the cheese. You can also add other toppings like cooked sausage, olives, or jalapeños for added flavor.
3. Finish with Parmesan: Sprinkle the grated Parmesan cheese over the top for an extra cheesy crust that will melt beautifully in the oven.

STEP 6: BAKE

1. Bake the Dish: Place the dish in the preheated oven and bake for 25-30 minutes, or until the cheese is melted and bubbly, and the edges are golden brown. The aroma that fills your kitchen will be irresistible!

STEP 7: REST AND SERVE

1. Let It Cool: Once baked, remove the dish from the oven and let it rest for about 10 minutes before serving. This allows the layers to set, making it easier to slice.
2. Garnish: If desired, top with fresh basil leaves for a pop of color and flavor. This simple touch can elevate the dish visually and taste-wise.