Heat olive oil in a large pot over medium heat.
Add diced onion and sauté for 3-4 minutes until translucent.
Add minced garlic and cook for 1 minute until fragrant.
Add diced zucchini, red bell pepper, and cherry tomatoes to the pot. Stir and cook for 3 minutes.
Pour in the vegetable broth and add the penne pasta, dried oregano, dried basil, crushed red pepper flakes, salt, and black pepper.
Bring the mixture to a boil, then 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 grated Parmesan cheese and chopped fresh parsley.
Adjust seasoning with additional salt and pepper if needed.
Serve hot, garnished with extra Parmesan and parsley if desired.