Ice Cream-Only Ice Cream Cake

Combine 3 tablespoons of the cold water and 3 teaspoons of the gelatin in a small microwavable bowl; let stand 5 minutes. Microwave on HIGH until gelatin melts, 8 to 10 seconds (do not let boil). Stir 1/4 cup of the heavy cream into gelatin mixture; set aside.

Beat together 2 3/4 cups of the heavy cream, 3/4 cup of the powdered sugar, and 3/4 teaspoon of the vanilla with whip attachment of an electric mixer at medium-high speed until thickened, about 2 minutes. Gradually add gelatin mixture, beating on low speed. Increase to high speed, and beat until stiff peaks form, about 1 minute.

Scoop ice creams into 1/2 cup round scoops. Arrange about 12 scoops of assorted flavors in bottom of an angel food cake pan, pressing ice cream scoops close togeather to avoid gaps. Spread about 2 cups whipped cream over ice cream. Repeat layers of ice cream and whipped cream until pan is full (you should have about 3 layers of each). Cover with plastic wrap, and freeze at least 4 hours or overnight. 

Place remaining 2 tablespoons cold water and 2 teaspoons gelatin in a small microwavable bowl; let stand 5 minutes. Microwave on HIGH until gelatin melts, 8 to 10 seconds (do not let boil). Stir 1/4 cup of the heavy cream into gelatin mixture. Beat together remaining 1 3/4 cup heavy cream, 1/2 cup powdered sugar, and 1/2 teaspoon vanilla with whip attachment at medium-high speed until mixture thickens, about 2 minutes. Gradually add gelatin mixture, beating on low speed. Increase to high speed, and beat until stiff peaks form, about 1 minute.

To remove ice cream cake from pan, dip pan into a large bowl of hot water 10 to 15 seconds. Loosen sides with a large spatula. Invert ice cream cake onto a serving plate. Frost top, sides, and center of ice cream cake with whipped cream. Place in freezer at least 1 hour, or until ready to serve.