pasta primavera recipe

Ingredients**: - 12 oz pasta (like penne or farfalle) - 2 tbsp olive oil - 1 small onion, thinly sliced - 3 cloves garlic, minced - 1 red bell pepper, thinly sliced - 1 yellow bell pepper, thinly sliced - 1 zucchini, thinly sliced - 1 cup cherry tomatoes, halved - 1 cup broccoli florets - 1/2 cup peas - 1/2 cup grated Parmesan cheese - 1/4 cup chopped fresh basil - Salt and pepper to taste - Lemon zest and juice from one lemon (optional) - Red pepper flakes (optional, for a bit of heat)