Preheat oven to 400°F. Add flour, baking powder, sugar, and salt to Mix n Blend II blender jar. Secure lid and press "Pulse" 3–5 times to sift dry ingredients. Add butter to jar and secure lid. Pulse until butter is pebble size. Add egg yolks, most of egg whites, and cream.
Move dough to floured board, pat dough and roll to ¾" in thickness. Cut in squares, brush with reserved egg whites, sprinkle with sugar, and bake for 12–15 minutes.