are you talking of white sauce? I mixed fat free Greek yogurt with ranch dressing and it was yummy...still a bit high in calories but lower then a normal ranch pizza. I also hear people use coli flowers but aim not that brave lol

Its not going to be the same, but ultra skim milk is has a thickener in it that makes it taste like 2%. You could use that and some unflavored gelatin to give it a more 'alfredo' texture. Add fresh garlic and a little white onion so minced that its almost like a paste. Add a tbsp or 2 of Parmesan, some oregano, salt and pepper and just keep seasoning until it's the way you like it.

I know a lot of people are turned off by using knox gelatin to thicken things, but it's the same as using corn starch or flour but with WAY less calories.

Anyway, my favorite white pizza is that sauce, roasted chicken, very slightly pickled red onions, steamed broccoli florets, and fresh spinach. Little bit of Mozzarella on top.

The 'pickled' onions are just thinly sliced red onions that have sat in a little bit of apple cider vinegar, lemon juice, and salt, for about an hour. It takes that raw bite away but still leaves all of the crispness and the flavor.