Bring a large pot of lightly salted water to a boil. Add tortellini and cook according to package directions, about 3-5 minutes until tender but not mushy. Reserve 1/4 cup of pasta water, then drain.

Heat olive oil in a large skillet over medium-high heat. Add chopped onion and sauté for 3 minutes until softened. Add corn and sauté for 2 minutes. Add cherry tomatoes and sauté for 3 minutes. Add zucchini and garlic, cooking until tender, about 6-8 minutes.

Drain tortellini and add it to the skillet with the vegetables along with marinara sauce. Cook and toss for 1-2 minutes until heated through. Add reserved pasta water if sauce is too thick. Season with salt and pepper. Stir in 1/4 cup parmesan cheese, basil, and parsley. Serve with remaining parmesan on top.