In a large bowl, cream butter and sugar until light and fluffy.
Beat the egg whites slightly
Add it to the butter mixture and then beat in extracts.
Combine the flour, baking powder, baking soda and salt
gradually add to the creamed mixture
alternately with yogurt
Pour half of the batter into a greased 9-in. x 5-in. loaf pan.
Combine topping ingredients;
sprinkle two-thirds over the batter.
Top with remaining batter.
Sprinkle with remaining topping; press down lightly.
Bake at 350° for 60-70 minutes or until a toothpick inserted near the center comes out clean.
Cool for 10 minutes before removing from pan to a wire rack.