Prepare cake according to directions; pour into three 9" greased and floured cake pans. Set aside.
Beat egg whites and sugar until stiff. Stir in chopped walnuts. Spread evenly over unbaked cake batter. Bake as directed on cake mix box.
Whip heavy cream. Fold in pineapple and powdered sugar. When cake is cooled, turn out and assemble into three layers spreading whipped cream mixture between layers and on the top and sides. Garnish with maraschino cherries.