From 500 Cupcakes, this buttercream is ideal if you want to make fancy designer cupcakes.
• 225g butter (or margarine if DF)
• 115g vegetable shortening
• 4 egg whites
• 2 teaspoons lemon juice
• ½ teaspoon cream of tartar
• 100g sugar
• 60ml (4 T) water
• 2 teaspoons vanilla essence
• Food colouring, if necessary
• Beat the butter and shortening together in a food processor until smooth; set aside in a cool area.
• Using a stand mixer, beat the egg whites with the lemon juice and cream of tartar until soft peaks form; set aside.
• Stir the sugar and water together in a saucepan until the sugar has dissolved. Cook over medium-high heat until a sugar thermometer inserted in the syrup registers 120°C (250°F) (about 10 minutes).
• Pour the hot syrup in a thin stream into the beaten egg whites, beating constantly at low speed until you have a thick, glossy icing. Beat in the vanilla and food colouring (if using).
• Continue beating on medium speed until the bottom of the bowl is as warm as your hands, about 36°C (98°F). Set aside to cool for five minutes.
• Switch to paddle attachment or a wooden spoon. Add the butter mixture, two tablespoons at a time, beating/mixing well after each addition until smooth and creamy.
• Cool for about an hour before using.