In a mixing bowl, combine flour and sugar. Cut in butter until crumbly. Set aside 3/4 cup for topping. Add the baking powder, milk, and egg yolks to remaining mixture, mix well. Beat eggs whites until soft peaks form, fold into batter.
Pour into 13X9 baking dish. Sprinkle with blueberries and reserved crumb mixture. Bake at 350 degrees for 30-35 minutes or until golden brown.