Step 1

Preheat the oven to 350°F. Line the bottom of a 9" cake pan with parchment paper or butter and flour the bottom of the pan. You don't need to butter/flour the sides of the pan. Sift together the flour, baking powder and salt, set aside.

Step 2

Cream the butter and 1/2 the granulated sugar until light and aerated, about 1-2 minutes. Add the egg yolks and vanilla, mix until combined. Mix in the sifted dry ingredients, don't over mix. Whisk the melted chocolate into the batter.

Step 3

Whip the egg whites to soft peak. Slowly add the remaining sugar and whip to full peak. Fold the egg whites into the batter in 3rds, mixing just until there are no streaks of egg white visible.

Step 4

Pour the batter into the prepared pan, spread to an even level and bake until the middle of the cake springs back when pressed or a toothpick inserted into the middle comes out clean, about 45-50 minutes.

Step 5

Cool for 10 minutes in the pan then turn out onto a cooling rack until completely cooled (see note).

Step 6

Stir the rum into the apricot preserves.

Step 7

Using a serrated knife, trim the top of the cake so it's flat. Split the cake horizontally into 2 layers. Place the bottom layer onto an 8" cardboard cake round (it makes handling the cake easier). Spread 1/3 of the apricot mixture onto the bottom layer and place the top layer onto the cake.

Step 8

Warm the remaining apricot preserves in the microwave for 30 seconds. Strain the preserves into a clean bowl to remove the chunky bits of fruit. Ice the top and sides of the cake with the strained apricot preserves. Place the cake onto a cooling rack set over a clean sheet pan. Allow the cake to air-dry for at least an hour.

Step 9

Microwave the the chocolate with the butter in 30 second increments until both are melted. Add the corn syrup to the chocolate/butter mixture. Pour the warm glaze over the cake, using a small spatula to fill in any gaps. Allow the glaze to set before moving to a serving platter.

Step 10

For the traditional design, pipe the word "Sacher" onto the cake using melted chocolate. You can use any extra glaze to pipe a border on the cake. Store and serve at room temperature.

Step 11

The assembled cake will improve for a day or two after being iced as the apricot preserves absorb into the cake.