Mousseline Buttercream

Total Time: 30 mins Preparation Time: 30 mins

Ingredients

• 2 cups unsalted butter (softened but cool, not runny and greasy)
• 5 large egg whites
• 1 cup sugar
• 1/2 teaspoon cream of tartar, plus
• 1/8 teaspoon cream of tartar
• 1/4 cup water
• 5 ounces dark chocolate or 6 ounces chocolate (chocolate melted and cooled) or 6 ounces fruit puree or 6 ounces fruit curds

Recipe

• 1 in a mixing bowl beat the butter until smooth and creamy and set aside in a cool place.
• 2 have all other ingredients at room temperature.
• 3 have ready a heatproof pouring container ready for the sugar syrup.
• 4 in a small heavy saucepan heat 3/4 cup sugar and the 1/4 cup water, stirring constantly, until the sugar dissolves and the mixture is bubbling.
• 5 stop stirring and reduce the heat to low.
• 6 (if using an electric range remove from the heat.) in the bowl of a stand mixer unsing the whisk attachment, beat the egg whites until foamy, add the cream of tartar, and beat until soft peaks form when the beater is raised.
• 7 gradually beat in the remaining 1/4 cup sugar until stiff peaks form when the beater is raised slowly.
• 8 increase the heat and boil the syrup until the thermometer registers 248'f to 250'f (the firm ball stage).
• 9 immediately transfer the syrup to the heatproof container to stop the cooking.
• 10 pour a small amount of syrup over the whites with the mixer off.
• 11 immediately beat at high speed for 5 seconds.
• 12 stop the mixer and add a larger amount of syrup.
• 13 beat at high speed for 5 seconds.
• 14 continue with the remaining syrup.
• 15 for the last addition, use a rubber scraper to remove the syrup clinging to the heatproof container.
• 16 lower speed to medium and continue beating up to 2 minutes or until the bottom of your mixing bowl feels cool to the touch.
• 17 if not completely cool, continue beating on lowest speed.
• 18 beat in the butter at medium speed 1 tablespoon at a time.
• 19 at first the mixture will seem thinner but will thicken beautifully by the time all the butter is added.
• 20 if at any time the mixture looks slightly curdled, increase the speed slightly and beat until smooth before continuing to add more butter.
• 21 when butter is fully incorporated you may add any of the optional flavorings.
• 22 place in an airtight bowl.
• 23 rebeat lightly from time to time to maintain silky texture.
• 24 buttercream becomes spongy on standing.
• 25 will keep 2 days room temperature, 10 days refrigerated, 8 months frozen.
• 26 allow to come to room temperature completely before rebeating to restore texture or it will break down irretrievably.