FROSTING FOR PETITS FOURS

Steps:

• In a saucepan, stir together the white sugar, cream of tartar and water. Bring to a boil over medium-high heat, and cook without stirring until the temperature is between 223 and 234 degrees F (106 to 112 degrees C), or until a small amount of syrup dripped from a spoon can spin a long thread.
• When the syrup comes to the proper temperature, remove from heat, and stir in confectioners' sugar about 1/2 cup at a time until the icing is thick enough to coat a metal spoon. (You may use a food processor for this step.) Test by pouring over a small piece of cake. Adjust the amount of confectioners' sugar as needed to get a good pouring consistency.
• Use while warm, or reheat over simmering water. Keep covered with plastic wrap when not in use to prevent a crust from forming on the top.
• To decorate cakes: place sliced petits fours on a cooling rack set over a jelly roll pan. Pour the frosting over the cakes, moving slowly down each row and back again, letting the icing spread over the cakes and drip down through the rack. You can re-use icing by reheating it.
• When the frosting has set and the cakes are dry, lift them from the rack with a spatula and trim the bottom edges with a sharp knife. Decorate as desired.