orange peel, grated
Cream butter and 1 1/2 cups sugar until light and fluffy; beat in egg yolks one at a time.
Fold in beaten egg whites.
Sift together flour, baking powder, baking soda and salt, and add to batter a little at a time, alternating with sour cream; stir until smooth.
Mix in grated orange peel and walnuts and pour into buttered 9" tube pan; bake 50 minutes at 350 degrees.
Puncture around the top of the cake with a fork. Mix remaining sugar with orange juice and amaretto and spoon over cake as soon as it comes out of oven.
Cool before removing from pan.