For the sponge cake: Preheat the oven to 400°F (200°C). Separate the egg whites from the yolks.

Whisk the yolks with the sugar until the mixture is pale and creamy.

Beat the egg whites with the salt until stiff peaks form.

Add the powdered sugar and beat the whites again.

Gently fold the egg whites into the yolk and sugar mixture.

Gradually add the flour, mixing well each time.

Line a baking sheet with parchment paper and butter it.

Spread the batter evenly with a spatula. Bake for 10 minutes, lowering the oven temperature to 350°F (180°C).

Line a loaf pan with plastic wrap.

Remove the sponge cake from the oven; it should be soft and golden.

Cover the sponge cake with a damp towel until completely cooled.

Prepare the espresso.

Brush the strip with coffee to soak it.

Add a layer of vanilla ice cream.

Fold the plastic wrap over the cake to cover it well. Place in the freezer.

For the meringue: Beat the egg whites until stiff peaks form. Add one-third of the sugar and beat again, then add the remaining sugar. The meringue should be firm and form peaks. Remove the cake from the mold, take off the plastic wrap, and place it on a serving platter that is oven-safe. Cover with meringue using a spatula, then decorate with a piping bag if desired.

Pipe a border of meringue around the base to seal in the ice cream. Return to the freezer until ready to serve.

Preheat the oven to 425°F (210°C) on broil. Bake the Baked Alaska for 5 minutes. Heat the rum in a small saucepan, ignite it, and pour it over the Baked Alaska.