In the bowl of a stand mixer, combine 1 cup of the flour, sugar, salt, and yeast; blend well.
In a small saucepan, heat the half & half and butter until very warm (120 to 130° F).
Add the warm liquid, pureed sweet potatoes*, and egg to the flour mixture.
With the paddle attachment, blend at low speed until moistened. Beat for 2 minutes at medium speed.
With the dough-hook attached, blend in the remaining 3 cups of flour for a soft dough. The dough will be somewhat sticky.
On a floured surface, knead the dough until smooth and elastic, about 2 minutes.
Place the dough in a greased bowl; cover loosely with a cloth towel and let rise in warm place until light and doubled in size, about 45-55 minutes.
Grease 2 baking sheets. Punch down the dough several times to remove all air bubbles. On a floured surface, toss the dough lightly until no longer sticky.
Divide the dough into 18 pieces; shape into balls. Place 2" apart on the baking sheets.
Cover; let rise in warm place until doubled in size, about 30 to 40 minutes.
Heat oven to 375°. Uncover the dough. Bake 15 to 20 minutes or until golden brown. Remove from baking sheets and cool on wire racks.
Brush with melted butter, or better yet, melted Rodelle's Vanilla Bean Butter.
