Whole Grain Waffles with Fruit and Maple Syrup

For the waffles: Beat the butter and sugar until light and fluffy. Separate the eggs and beat the egg yolks with the butter and sugar. Whip the egg whites with the salt until stiff. Combine the baking powder with the whole wheat flour and alternately add the flour and yogurt to the butter mixture. Add milk until a smooth, fluid dough has formed. Finally, fold in the egg whites. Butter the waffle iron and place a tablespoon of batter in the center of each waffle press. Continue until all the waffles are made, adding more or less batter as needed for the waffle iron.