Preheat the oven to 325°F
Spray 8x8 pan with Pam with flour
Using whip attachment, beat whites to stiff peaks.
Set aside and beat yolks with powdered sugar until pale yellow.
Add butter and water.
Add flour, mixing well.
Slowly add milk and vanilla.
Mix in whites a little at a time until pretty well blended. Some lumps may remain.
Bake 40-50 mins.
Top should be browned and center wiggly.
While cooling, stir berries and sugar and let sit until cake is cooled.
Once cool, cut squares, dust with powdered sugar and top with berries!
Add whipped cream if desired!