Heat water in a pan and bring to water to a boil. Add the broccoli and cook for 2 to 3 minutes or until fork tender. Remove with a slotted spoon and set aside.
Cook the tortellini according to the directions on the package.
While the tortellini is cooking prepare the sauce for the dish. In a large skillet melt the butter. Add the garlic and basil cook for a minute or two until the garlic softened.
Mix the cornstarch with chicken broth. Add the broth to the skillet and bring to a boil and cook until the sauce begins to thicken. Add the lemon zest and stir in.
Stir in the tortellini, chicken, and broccoli and simmer for 3 to 5 minutes, so to warm the chicken and broccoli. Add the Parmesan cheese and stir in. Season with salt if needed.