Preheat oven to 350 degrees.
Start by making the Alfredo sauce by placing milk, low fat cream cheese, flour and salt in a blender and blend it until it is completely smooth.
Meanwhile, in a skillet over medium heat, melt one tablespoon of butter and garlic for a minute. Whisk in the blended milk mixture, stirring constantly for 3-5 minutes.
Continue stirring the sauce over heat until it reaches your desired thickness, then mix in Parmesan cheese.
Once your sauce is ready (or if you don't make homemade Alfredo sauce, feel free to use jarred sauce), it's time to assemble the casserole.
Spray a 9 x 13 inch baking dish with non-stick cooking spray.
In the baking dish, mix together Alfredo sauce, frozen tortellini (don't cook it first), chicken broth, seasonings, chicken and frozen vegetables.
Cover pan with aluminum foil and bake for 30 minutes.
Remove pan from oven, sprinkle casserole with Parmesan cheese, and place the pan back in the oven (uncovered) for another few minutes or until the cheese is melted.