. pure vanilla extract ½ teaspoon . . Beat the Butter In the bowl of a stand mixer fitted with the flat beater, beat the butter on medium-high speed until creamy, about 1 minute. Set aside in a cool place (no higher than 70°F/21°C). Prepare the Egg Whites Pour the egg whites into the bowl of a stand mixer, if you have a second bowl, or into a medium bowl and have ready a handheld mixer. Heat the Sugar Syrup Have ready a 1-cup or larger heatproof glass measure. In a small heavy saucepan, preferably nonstick, stir together ¼ cup plus 2 tablespoons of the sugar and the water until all of the sugar is moistened. Heat on medium, stirring constantly, until the sugar dissolves and the mixture is bubbling. Stop stirring and reduce the heat to low. (If using an electric range, remove the pan from the heat.) Beat the Egg Whites If using the stand mixer for the egg whites, attach the whisk beater. Beat the egg whites on medium speed until foamy. With the mixer off, add the cream of tartar.
