Heat oven to 350° F. Cream sugar and butter together; add vanilla. Sift flour, then sift again with baking powder. Alternately add flour mixture and coffee to creamed mixture. Fold in pecans and egg whites. Bake in greased 8-inch square pan for 40 to 50 minutes. Cool. Prepare the following icing.
Icing:
*Boil sugar and coffee together until syrup threads. While sugar is cooking beat egg white until foamy; add cream of tartar and beat stiff. Pour hot syrup into the beaten egg white; beat until peaks form. Spread over cake and sprinkle with pecans.