This is one of those simple quick recipes that allows you to put food on the table in a 1/2 hour or less. The measurements used here need not be exact, it is depending on how thick you want the sauce, you can increase the flour or the milk depending on whether you want it thicker or thinner. I sometimes use this to use up left over broccoli, asparagus or mushrooms that are in the refrigerator. Depending on the vegetables, you can also substitute the Parmesan for sharp or medium cheddar. For an extra zing, add 2 or 3 tablespoons of dry full bodied white wine to the sauce.