Place the cake slices on a baking sheet lined with parchment paper.
Cut the ice cream into about 1" thick slices. (see notes)
Cover the cake slices with ice cream. Place these in the freezer while you prepare the meringue.
Beat the room temperature egg whites at high speed until they form a stiff, but not dry, meringue. Add the sugar near the end of the beating time.
Remove the prepared cake and ice cream layers from the freezer and cover each with meringue, making sure to seal the meringue all the way down to the parchment.
Bake in a hot oven for 6-8 minutes or until the meringue is golden brown.
Remove from the pan with a spatula and serve immediately.
The recipe is much easier to assemble if you purchase ice cream that comes in a box rather than a tub. The rectangular shape of boxed ice cream lends itself to being cut into "slabs" that fit nicely onto slices of cake.At about the 5-minute mark of baking, start watching carefully and if you note a little melted ice cream starting to flow out from the Baked Alaskas, remove them from the oven immediately.