In a large skillet, melt the butter. Whisk in the flour and then quickly whisk in the milk, making sure that the flour doesn't clump in the milk. Bring to bubbling over medium high heat and let the sauce thicken.
Cook the frozen veggies as directed and drain well. You don't want any extra water in the veggies thinning out the sauce.
Once thickened, stir in the Parmesan cheese, shredded mozzarella cheese, garlic powder and salt and pepper to taste. Mix in the prepared veggies.
Prepare pasta as directed.
Serve Veggie Alfredo Sauce over pasta.
To Freeze: Completely cool the sauce with veggies in the refrigerator and spoon into a plastic freezer baggie. Remove as much air from the baggie as you can and then flat freezeto save space.
To Thaw: Place the baggie in a bowl of warm water to quickly thaw it. (Or let thaw in the refrigerator overnight.)
To Reheat: Add thawed or partially frozen sauce to a skillet and reheat for 10-15 minutes over medium low heat, stirring often.