Preheat oven to 375°F.
In a 9×13 baking dish, combine tortellini, cooked ground beef, marinara sauce, and chopped zucchini. Stir to mix well.
Sprinkle shredded cheddar cheese evenly over the top.
Cover tightly with foil and bake for 35-40 minutes, until the tortellini is tender and heated through. Alternatively, remove from oven after 30 minutes, add cheese, and bake uncovered for 5-10 minutes until cheese is bubbly.
Let sit 5 minutes before serving.
