Transfer enough raspberry sorbet to fill the cavities of a 6-cavity silicone half-sphere mold with 2.75-inch diameter cavities. Use a small offset spatula to smooth the sorbet to a level finish. Freeze for at least 2 hours before assembling the baked Alaska.
Line a 9 x 4 x 4-inch Pullman loaf pan with parchment paper, so a significant amount hangs over the long sides. Add a thin layer of raspberry sorbet to the bottom of the pan and place in the freezer for at least 2 hours. Freeze the remaining sorbet for another use in an airtight container for up to 3 months.
Remove the pan from the freezer after 2 hours. It’s time for the next layer. Add about half of the lime ice cream in an even layer over the first sorbet layer.
Unmold 2 of the half spheres of raspberry sorbet and stick them together to form a full sphere. Place the sphere of sorbet into the layer of lime ice cream. Repeat with the remaining 4 half spheres. Cover with the remaining lime ice cream. To make a cake base, cut a super thin layer of pound cake and trim off the browned edges. Place it on top of the lime ice cream and trim the cake to fit the pan, adding more cake as needed. You can use any thin cake you like. Using a layer of cake for the bottom helps to keep the baked Alaska from sliding around on the serving plate and makes serving easier.
Place the loaf pan back in the freezer and freeze until frozen solid, at least 4 hours.
Remove the loaf pan from the freezer and invert it over a serving plate or cold marble slab. If the ice cream won’t come out, heat the pan by wrapping it with a hot towel or wave it with a blowtorch.
Remove the parchment paper. Cover the baked Alaska with the meringue using a large offset spatula. To create curls, take a blob—yes, a blob—of the meringue between your fingers and press it against the meringue on the cake. Pull the blob away from the cake, it will break off in a wispy curl. The thicker the blob you lay down as a foundation on the cake, the bigger the curls will be. It may take a few times to get the hang of it, but then you’ll be off and running. Plus, it’s fun. Freeze until ready to serve.
Right before serving, toast the meringue with a kitchen blowtorch: hold the blowtorch about 3 inches from the cake, so just the tip of the flame is hovering over the cake. Keep the torch moving so it doesn’t burn the meringue. The tip of the curls will set fire, which is not as scary as that sounds but you need to blow them out as you go. The burnt tips are a lovely contrast and add a wonderful flavor.
Slice the baked Alaska with a knife that’s been dipped in hot water to cleanly cut slices.