Line two greased 9-in. round baking pans with waxed paper and grease the paper; set aside. In a large bowl, cream butter and 3/4 cup sugar. Add egg yolks, vanilla and orange zest; mix well. Combine flour, baking powder and salt; add to creamed mixture alternately with milk and orange juice., In another bowl, beat egg whites on medium speed until soft peaks form. Gradually beat in remaining sugar, 1 tablespoon at a time, on high until stiff glossy peaks form. Fold into batter., Pour into prepared pans. Bake at 350° for 18-22 minutes or until a toothpick comes out clean. Cool for 10 minutes before removing from pans to wire racks. Gently peel off waxed paper and discard. Cool cakes completely., In a bowl, combine the chopped strawberries and sugar; let stand for 30 minutes. In a bowl, beat cream and vanilla until cream begins to thicken. Gradually beat in confectioners' sugar on high until stiff peaks form. Fold in sour cream., Place one cake layer on a serving plate; top with chopped berries and half of the cream mixture. Top with the remaining cake and cream mixture. Garnish with whole berries.