Blueberry Cake

recipe from here
Ingredients
1/2 cup butter
1/2 cup white sugar
1/4 teaspoon salt
1 teaspoon vanilla extract
2 egg yolks
1 1/2 cups all-purpose flour
1 teaspoon baking powder (i use 3/4 tsp baking soda + 1 tbsp vinegar)
1/3 cup milk
2 egg whites
1/4 cup white sugar
1 1/2 cups fresh blueberries
1 tablespoon all-purpose flour
1 tablespoon white sugar
Method

1. Preheat oven to 350 degrees F (175 degrees C). Grease and flour an 8 inch square pan. (I use a rectangular baking pan.)
2. Cream butter or margarine and 1/2 cup sugar until fluffy. Add salt and vanilla. Separate eggs and reserve the whites. Add egg yolks to the sugar mixture; beat until creamy.
3. Combine 1 1/2 cups flour and baking powder; add alternately with milk to egg yolk mixture. Coat berries with 1 tablespoon flour and add to batter.
4. In a separate bowl, beat whites until soft peaks form. Add 1/4 cup of sugar, 1 tablespoon at a time, and beat until stiff peaks form. Fold egg whites into batter. Pour into prepared pan. Sprinkle top with remaining 1 tablespoon sugar.
5. Bake for 50 minutes, or until cake tests done.