In a very large mixing bowl bring egg whites to room temperature. Meanwhile, sift powdered sugar and flour together 3 times. In a small mixing bowl stir together 1 tablespoon of the flour mixture and the crushed candies. Set the flour mixture and the candy mixture aside. Add cream of tartar and vanilla to the egg whites. Beat with an electric mixer on medium to high speed until soft peaks form (tips curl). Gradually add sugar, about 2 tablespoons at a time, beating on medium to high speed until stiff peaks form (tips stand straight). Sift about one fourth (1/4) of the plain flour mixture over the egg white mixture, then gently fold in. Repeat sifting and folding in the remaining flour mixture, using one fourth (1/4) of the flour mixture each time. Gently fold in the candy mixture. Gently pour the batter evenly into an ungreased 10 inch tube pan. Gently cut through the cake batter with a knife or narrow metal spatula. Bake on the lowest rack in a 350F oven for 40 to 45 minutes or until the top springs back when lightly touched. Remove from oven. Immediately invert the cake in the pan and cool completely. Using a narrow spatula, loosen the sides of the cake from the pan. Then remove the cake from the pan.