Preheat oven to 375 degrees F (190 degrees C).

Beat egg whites until foamy.

Gradually add sugar to the egg whites, beating until stiff peaks form.

In a separate bowl, beat egg yolks with vanilla until thick and lemon-colored.

Fold the egg yolk mixture into the egg white mixture.

Sift together flour, cocoa, baking powder, and salt.

Gently fold the dry ingredients into the egg mixture.

Pour batter into a wax paper-lined 10 x 15 x 1 inch pan.

Bake for 13-15 minutes.

Invert the cake onto a towel sprinkled with cocoa powder.

Remove the wax paper and trim the crisp edges from the cake.

Roll up the cake with the towel and chill for 30 minutes.

Unroll the cake and remove the towel.

Whip heavy cream with powdered sugar until soft peaks form.

Mix in sliced almonds and candied ginger.

Spread orange marmalade evenly over the cake.

Spread the whipped cream mixture over the marmalade.

Reroll the cake tightly, placing it seam-side down on a serving platter.

Bring water to a boil.

Stir in powdered sugar and cocoa until smooth.

Blend in vanilla and butter; let cool slightly.

Glaze the cake with the chocolate mixture.

Garnish with the remaining toasted sliced almonds.