01 - Line a 9-inch bowl with plastic wrap. Press softened ice cream into the bowl, removing any air pockets. Smooth the surface, cover, and freeze until firm, at least 4 hours.
02 - Place the sponge cake on a parchment-lined baking sheet. Unmold the ice cream from the bowl and invert onto the cake. Return to freezer while preparing meringue.
03 - Preheat oven to 450°F or prepare a kitchen torch for toasting the meringue.
04 - In a clean, dry bowl, beat egg whites with cream of tartar until soft peaks form. Gradually beat in sugar until stiff, glossy peaks develop. Beat in vanilla extract.
05 - Quickly spread meringue over the ice cream and cake, sealing completely. Create decorative swirls.
06 - Bake for 3 to 5 minutes until golden or use a kitchen torch until browned. Serve immediately or freeze up to 2 hours before serving.