To a large Dutch oven or pot over medium heat, add the oil. Once hot, add in the minced garlic, bell peppers, and onion. Cook for 3-4 minutes to start to soften the vegetables. Add in the zucchini and sliced mushrooms and cook for an additional 3 minutes, stirring occasionally.
Add in the tomato paste, Italian seasoning, broth, marinara sauce, and pasta. Stir and bring to a simmer and cover.
Turn heat to low and let simmer, stirring occasionally, for 12-15 minutes, or until the pasta is tender. If too much liquid boils out, you can add 1/3 cup of water. Once the pasta is tender, stir in the cheese, let melt, and serve. Enjoy!