Preheat oven to 350º.
Grease a 9x13” baking dish and set aside.
Wash blueberries in a colander.
Set blueberries out on paper towels and pat dry; set aside.
In two small bowls separate egg yolks from egg whites.
Set aside.
In a large mixing bowl, combine flour and granulated sugar.
Cut in butter with a pastry blender until crumbly and coarse crumbs form.
Measure out ¾ cup for topping; set aside.
To remaining flour mixture, add baking powder, half-and-half and egg yolks.
Mix well.
In a separate bowl, beat egg whites until soft peaks form.
This will take about 3-5 minutes.
Fold egg whites into the batter.
Pour mixture into prepared baking dish.
Sprinkle blueberries over top of the batter in baking dish.
Add reserved crumb mixture over top and sprinkle evenly over top of the blueberries.
Bake at 350º for 30-35 minutes until cake is lightly golden brown and a toothpick inserted in center comes out clean.
Cool before cutting into bars.