1 (16 ounce) package penne pasta
1 tablespoon olive oil
2 zucchini, chopped
2 yellow squash, chopped
1 red onion, chopped
1 red bell pepper, chopped
1 green bell pepper, chopped
1 tablespoon crushed garlic
1 (28 ounce) can diced tomatoes, drained (Chop and squeeze/drain fresh tomatoes as an alternative. - Nica)
1 (28 ounce) jar chunky style pasta sauce
1 (15.25 ounce) can whole kernel corn, drained
1 teaspoon crushed red pepper, or to taste
1/2 teaspoon black pepper, or to taste
2 cups shredded mozzarella cheese
Fill a large pot with lightly salted water and bring to a rolling boil over high heat. Once the water is boiling, stir in the penne, and return to a boil. Cook the pasta uncovered, stirring occasionally, until the pasta has cooked through, but is still firm to the bite, about 11 minutes. Drain well in a colander set in the sink, place the pasta in a large bowl, and set aside.
While the pasta is cooking, heat the oil in a large skillet over medium heat, and cook and stir the zucchini, squash, onion, red and green peppers, and garlic until the vegetables are tender, for about 10 minutes. Pour in the tomatoes, pasta sauce, and corn, and stir to mix. Sprinkle with red and black pepper to taste, and bring the mixture back to a boil. Simmer for 20 minutes.
Preheat an oven to 350 degrees F (175 degrees C). Grease a 9x13 inch baking dish.
Pour the vegetable mixture into the bowl with the cooked penne pasta, stir to mix well, and spoon into the prepared baking dish. Sprinkle the mozzarella cheese over the top, and bake in the preheated oven until the cheese is melted and the casserole is bubbling, 20 to 30 minutes.