This recipe was submitted by First Lady Laura Bush to the New York Times for an article called "America Reaches For Tradition; Giving Thanks at the President's Table", by Marian Burros, Nov. 14, 2001. I believe she said that it wasn't her creation but that it originally came from a neighbor.
It has no sweetener of any kind, but you'd never guess. I've made this for Thanksgving a few times and everyone loves it. Last year, I used a sugared pecan for the topping, which went over well at dinner. If you're allergic to nuts, leave them out. It's still good.
Whatever you do, don't try this with boiled or canned sweet potatoes. It really needs the baking process to bring out the sweetness and keep the puree from being soupy. I learned that lesson the hard way.
Prep time doesn't include baking and cooling time for sweet potatoes.