Step 1

Preheat oven to 350 degrees F. Lightly coat a 13- x 9-inch baking dish with nonstick cooking spray.

Step 2

Bring a large pot of water to boil and add the tortellini. Cook for 2 minutes then promptly drain well and transfer it to the prepared baking dish. Add the fresh spinach to the hot tortellini and toss to combine, making sure that some of the tortellini ends up on top. Pour the marinara sauce evenly over the top and DON'T STIR. Sprinkle the crushed red pepper flakes (if using) and Parmesan over the top.

Step 3

Coat the underside of a sheet of foil with nonstick cooking spray and place it, coated side down on top of the baking dish. Crimp the edges and transfer to the oven. Bake for 20 minutes. Remove the foil and bake another 5 minutes or until heated through.