(total of 8 oz) unsalted butter, sliced about 1/2 inch thick, cool but not quite room temp (~60°F) • white sugar • baking powder • salt • large egg whites • heavy cream • vanilla extract • and 2/3 cups (11 ounces) bleached cake flour • (total of 8 ounces) unsalted butter, at room temperature • powdered sugar • freeze-dried raspberries • freeze dried blueberries •