Egg Wash: Beat egg with water. Brush the bun. Cut top of buns into a cross or if you would like you can just frost the tops into the shape of a cross. Bake buns for 20-21 minutes. Remove from oven and allow to cool. Frosting: With a hand blender blend the frosting ingredients together. Pipe frosting in a cross over the top of the buns. 12 buns.