1 lb. sweet potatoes, scrubbed
1 russet potato, scrubbed
2 tbsp. softened unsalted butter
1 lg. whole egg, beaten lightly
1 lg. egg yolk, beaten lightly
Melted unsalted butter for drizzling over the potatoes

Bake the sweet potatoes and the russet potato in a preheated 400 degree oven for 1 hour, or until they are tender. Halve the potatoes lengthwise scrape the flesh from the skins and force it through a ricer or food mill into a large bowl.

Beat in the softened butter, the whole egg, the egg yolk, and salt and pepper to taste and beat the mixture until it is smooth. Transfer the mixture to a pastry bag fitted with a tip and pip onto butter baking sheet. The rosettes may be prepared up to this point and covered loosely.

Chill for several hours or overnight. Bake the rosettes in a preheated 350 degree oven for 10-15 minutes if at room temperature, or 25-30 minutes if chilled, or until they are heated through. Put the baking sheet under a preheated broiler about 6 inches from the heat, and broil the rosettes until the tops are browned lightly.