To Make Ahead:
Prepare sweet potatoes as directed, except cover and chill egg whites. Do not preheat oven, but do cool sweet potatoes to room temperature after mashing. When cool, continue with Step 2. Cover tightly with foil; chill for up to 48 hours. To serve, let stand at room temperature for 30 minutes. Preheat oven to 350°F. Bake for 45 minutes; stir. Prepare meringue as directed in Step 3 (or spread with marshmallow creme). Bake as directed.
