In a third bowl, sift the two flours with DME, baking powder, baking soda and salt. Pour the flour ‘dry’ mixture into the yolk “wet’ mixture and lightly stir together, leaving a few lumps of flour. Do not overmix. Stir 1/3 of the beaten egg whites into the batter: This will loosen the batter. Fold in the next 1/3 of the whites and then the last addition, being gentle with the folding, keeping as much air from the whipped egg whites as possible in the batter.