INGREDIENTS
1 cup
cake flour
1 1/2 cups
granulated sugar
1/4 tsp
salt
12
large egg whites
1 tsp
vanilla extract
1 1/2 tsp
cream of tartar
1 stick
unsalted butter, softened
6 oz
fresh blackberries, pureed and strained
1/2 tsp
lemon juice
3 cups
powdered sugar
food coloring, if desired