– 2 ¼ cups cake flour – 1 tablespoon baking powder – ½ teaspoon salt – 1 ¼ cups buttermilk (see note) – 4 large egg whites (see note) – 1 ½ cups sugar – lemon zest from two large lemons – ½ cup unsalted butter , at room temperature – 1 teaspoon vanilla – ½ teaspoon lemon extract For the Frosting: – ⅔ cup fresh raspberries , frozen or thawed – ½ cup salted butter , at room temperature – ½ cup unsalted butter , at room temperature – ½ cup shortening – 1 tablespoon vanilla extract – 3 cups powdered sugar – 1-3 tablespoons milk , if needed