* Line two 9-in. round baking pans with waxed paper and grease the paper; set aside. In a large bowl, cream the shortening, butter and sugar until light and fluffy. Add eggs, one at a time, beating well after each addition. Beat in vanilla. Combine cracker crumbs and baking powder; add to the creamed mixture alternately with milk, beating well after each addition.
* Transfer to prepared pans. Bake at 350° for 18-22 minutes or until a toothpick inserted near the center comes out clean. Cool for 10 minutes before removing from pans to wire racks to cool completely.
* In a large heavy saucepan, combine the egg whites, sugar and cream of tartar over low heat. With a hand mixer, beat on low speed for 1 minute. Continue beating on low over low heat until frosting reaches 160°, about 8-10 minutes. Pour into a large bowl; add vanilla. Beat on high until stiff peaks form, about 7 minutes.
* Place a cake layer on a serving plate; spread with 2/3 cup frosting and sprinkle with half of chips. Top with remaining cake layer. Frost top and sides of cake; sprinkle with remaining chips. Yield: 12 servings.