Bring a large pot of salted water to a boil. Cook the rigatoni according to the package instructions; drain and set aside to cool.
Heat the olive oil in a skillet over medium heat. Add the garlic and onion and cook until the onions are golden, 3 to 4 minutes. Stir in the tomatoes and tomato paste until everything is mixed together. Add salt and pepper to taste. Bring to a simmer and cook for 10 to 15 minutes.
Preheat the oven to 350 degrees F.
Spread a thin layer of sauce in a 9-by-13-inch baking dish. Layer in half of the cooked noodles, half of the cubed mozzarella, 3 tablespoons Parmesan and half of the sweet peppers. Top with half of the remaining sauce. Repeat the process with the remaining noodles and mozzarella, 3 tablespoons Parmesan and the remaining peppers and sauce. Top with the remaining 3 tablespoons Parmesan. (If making ahead, cover and refrigerate.)
Cover and bake until the sauce is bubbling and the peppers are cooked through, about 40 minutes. Let sit 10 minutes before serving. Serve with Peppy Salad.
Add the lettuce, pepperoncini, tomatoes, onion and mini pepper to a bowl. Drizzle over the olive oil and lemon, then sprinkle over some salt and pepper and toss.