01 - Line an 8-inch bowl with plastic wrap, leaving an overhang. Pack the softened ice cream into the bowl, smoothing the surface. Cover and freeze until very firm, at least 4 hours or overnight.
02 - Place the sponge cake layer on a parchment-lined baking sheet. Unmold the ice cream dome onto the cake, removing the plastic wrap. Return to freezer while preparing meringue.
03 - In a clean, dry bowl, beat egg whites with cream of tartar until soft peaks form. Gradually add sugar, continuing to beat until stiff, glossy peaks develop. Fold in vanilla extract.
04 - Preheat the oven to 450°F or prepare a kitchen torch for toasting the meringue.
05 - Quickly spread meringue over the ice cream and cake, sealing all edges completely. Create decorative swirls on top.
06 - Bake in the preheated oven for 3 to 5 minutes until meringue is golden brown or toast evenly with a kitchen torch.
07 - Slice and serve immediately to preserve texture and temperature contrast.