Heat olive oil in a large pot over medium heat.
Add the chopped onion and cook for 3-4 minutes until softened.
Add the minced garlic and cook for 1 minute until fragrant.
Add the diced red bell pepper and zucchini to the pot and cook for 3 minutes, stirring occasionally.
Pour in the vegetable broth, diced tomatoes with their juice, and add the dried Italian seasoning, salt, and black pepper.
Bring the mixture to a boil.
Add the penne pasta to the pot, stirring to combine.
Reduce heat to medium-low and simmer uncovered for 12-15 minutes, stirring occasionally, until the pasta is cooked and most of the liquid is absorbed.
Remove the pot from heat and stir in the shredded mozzarella and grated Parmesan cheese until melted and creamy.
Sprinkle chopped fresh basil over the pasta before serving.