INGREDIENTS
4
lemons (freshly zested (about 2-3 tablespoons))
1 cup
sugar
1/2 cup
butter, melted
1 3/4 cups
all-purpose flour
1 1/2 tsp
baking powder
1/2 cup
milk
1/2 cup
sour cream
1 tsp
vanilla
2
large egg whites
1 cup
blackberries
2 tbsp
lemon juice
1 cup
butter, room temperature
4 cups
powdered sugar
1 tsp
vanilla
1 tbsp
milk or cream