Allow egg whites and yolks to stand at room temperature for 30 minutes. In a blender, combine the ¾ cup cantaloupe and 2 tablespoons of the sparkling wine. Cover and blend until smooth. Set aside. Grease and lightly flour a 10-inch fluted tube pan; set aside.
In a large bowl, combine the remaining sparkling wine and the 8 cups cantaloupe. Toss gently to coat. Cover and chill until ready to serve.
Preheat oven to 325°F. In a large bowl, combine cake flour, granulated sugar, baking powder, salt, and allspice. Make a well in the center of the flour mixture.
Add egg yolks, pureed cantaloupe mixture, and oil to flour mixture. Beat with an electric mixer on low speed until combined. Beat on high speed about 5 minutes more or until batter is very smooth. Wash beaters thoroughly with soap and warm water; dry beaters. In a very large bowl, combine egg whites and cream of tartar; beat with an electric mixer on medium speed until stiff peaks form (tips stand straight). Pour egg yolk mixture in a thin stream over beaten egg whites, folding gently as you pour. Pour into prepared pan; spread evenly.
Bake for 45 to 50 minutes or until top is golden brown and springs back when lightly touched. Immediately invert cake in pan; cool completely. Loosen sides of cake from pan; remove cake. Place cake on a serving plate. If desired, sprinkle with powdered sugar and garnish with fresh sage. Serve cake with chilled cantaloupe mixture and, if desired, dessert topping.
Tip: We do not recommend sugar substitutes for this recipe.