2 large egg whites
½ cup sugar
½ cup unsalted butter, room temperature, cut into tablespoons
½ teaspoon pure vanilla extract
¼ cup seedless raspberry preserves
1. Set the bowl of your electric mixer over a pan of simmering water. Add the egg whites and sugar to the bowl and whisk until sugar has dissolved . This should only take a few minutes.2. Take the bowl off the heat and attach to the mixer along with the whisk attachment. Beat the egg-white mixture on high speed until it holds stiff peaks. Continue beating on medium-low speed until the mixture is cooled, about 6 minutes. This step is important. If you don’t beat to stiff peaks and allow the mixture to cool, the frosting will end up runny. 3. Switch to the paddle attachment. With mixer on medium-low speed, add butter one tablespoon at a time, beating well after each addition. 4. Beat in vanilla. 5. Measure out preserves into a small bowl and whisk to soften. Fold preserves into the frosting with a rubber spatula until smooth
