Use this pretty-in-pink recipe to decorate our Lemon-Yogurt Cupcakes. Martha made this recipe on "Martha Bakes" episode 808.
Puree berries with granulated sugar in a food processor until smooth. Pass mixture through a fine sieve into a bowl, pressing on solids to extract as much liquid as possible.
In another bowl, beat butter on medium-high speed until pale and fluffy, about 2 minutes. Reduce speed to medium and add confectioners' sugar, 1/2 cup at a time, beating well after each addition and scraping down sides of bowl as needed. Beat in berry puree. Frosting can be stored in refrigerator up to 2 days; bring to room temperature and beat on low speed until smooth again before using.