My Mother's Version
For the Sponge Cake:
3 ounces chocolate (unsweetened, melted, and cooled to lukewarm)
3/4 cup (1 1/2 sticks) unsalted butter, softened
1/2 cup sugar
4 eggs (separated)
1 pinch salt
1/2 cup flour (all-purpose)
For the Filling:
1 1/2 cups heavy cream
10 ounces chocolate (semisweet, chopped)
4 tablespoons dark rum
1 teaspoon vanilla extract
For the Glaze:
7 ounces chocolate (semisweet, chopped)
2 tablespoons butter (unsalted)
2 tablespoons corn syrup (light)
1 teaspoon vanilla
For the cake:
Heat oven to 350 degrees.
Spray or brush a 9x11 pan with oil or butter.
Line with parchment paper. And spray the paper.
In a large bowl, cream the butter with 1/4 cup sugar until light and fluffy.
Beat in egg yolks one at a time.
Add cooled melted chocolate.
Beat egg whites, mid-way, add remaining 1/4 cup sugar and continue to beat until stiff peaks form.
Lighten the chocolate mixture by stirring in 1/3 of the whites. Then, carefully, fold in the remaining egg whites.
Sprinkle the flour over the batter and, carefully, fold it in without decreasing the volume.
Pour into prepared pan and bake about 25 minutes, or until cake starts to pull away from the sides. Do not overbake. Cool a few minutes on a wire rack and then invert onto the rack. Remove parchment paper and let cool completely.
For the filling:
Meanwhile, Place 10 ounces chocolate in a heatproof bowl. Bring the cream to a boil in the microwave or on the stovetop and pour over chocolate. Cover with plastic wrap and let stand 10 minutes. Add rum and vanilla and stir until smooth. Refrigerate 1 hour. When cold, whip the filling until the volume has doubled.
Assembly: Cut the cake in half and place one half on a rack. Spread the filling over the cake and top with the remaining cake half. Refrigerate for 1 hour.
For the glaze: Meanwhile, Place 7 ounces chocolate, butter and corn syrup in a microwaveable bowl. Heat on full power 1 minute. Add vanilla and stir until completely melted and smooth. Let cool 10 minutes.
Set the rack holding the cake over a pan to catch drips. Holding the glaze 2 inches above the cake, pour the glaze evenly, using a spatula to cover the sides, if necessary. Refrigerate 20 minutes or until glaze is set.
This cake is very rich. Cut into 5 by 7 rows for a total of 35 small squares. Refrigerate leftovers.