If you're dying for a creamy sauce, though, a healthy alternative is pureed cauliflower. It really does have a very thick, creamy consistency, and with a few spices makes a great sauce for chicken or pasta. Or you can just puree it with some cottage cheese, fresh basil and pepper and eat it with a spoon. YUM!
I've tried looking for recipes on how to make pureed cauliflower but they think I am looking for a healthy alternative to mash potatoes. Do you have a specific way of making it yourself?
My dear, it couldn't be easier. Steam the cauliflower until it's mushy when you poke it with a fork, then throw it in the blender.

Here are some helpful tips, though: Steaming is easy. If you don't already have one, you can get a cheap steaming basket, put it in a pot with enough water to reach the bottom of the basket, and set it on the burner on high. Steam the cauliflower until it's well-mushy, since you're going to blend it anyway; the extra cooking also gets rid of the gases to keep you from getting bloated and farty. Cooking time depends on how much you're making, so poke the biggest chunk with a fork every 10 minutes or so, and when that one's soft it's done.
In fact, if you're trying to go healthy, steam all your veggies! Veggies really have great flavor that a lot of people cover up with butters and oils and dressings and sauces, but with most veggies 20 minutes steaming, and maybe a pinch of salt is all you really need. I often steam my potatoes, even, because it's just so easy to throw the whole lot of veggies in the steaming basket and do them at once.
Anyway, back to the cauliflower, adding milk or low fat cottage cheese, a bit of fresh parsley, and a dash of black pepper and salt makes for a really nice creamy sauce. If you want a creamy tomato based sauce (like a sort of vodka sauce substitute) you could mix the cauliflower with marinara. Basically, you could use pureed cauliflower anywhere a recipe is using heavy cream as a thickener. For example, this is a great thickener for soups without all the added fat.
Also, as J noted, a great way to cut down on the carb load and calories of mashed potatoes is to either use cauliflower instead, or go half and half.
What you really need to do is just experiment. Cooking is all about experimentation. And healthy cooking isn't that hard to do -- steam or roast more often than frying, fewer ingredients is usually better, less meat, more veggies, fewer starchy veggies (carrots, potatoes, peas, etc), more fibrous veggies (green beans, leafy greens, etc).