As a first step in preparing our delicious Sacher Cake, melt the chocolate in small pieces over a double boiler.
If you choose to melt it in the microwave, heat it in short intervals, stirring at each pause to prevent the chocolate from burning.
Next, place the softened butter, powdered sugar, and a pinch of salt into the bowl of a stand mixer. Add the seeds from the vanilla pod and mix with the whisk at medium speed until the mixture is smooth and creamy.
Then, gradually add the lightly beaten egg yolks, preferably in two batches, and continue to mix for about 9 minutes.
To develop the batter properly, it is important that the mixture of powdered sugar, egg yolks, and butter is well aerated. Also, ensure the melted chocolate is between 45 and 55°C (113–131°F) so it doesn’t melt or stiffen the butter.
At this point, add the melted chocolate to the butter and yolk mixture and mix until fully combined.
Whip the egg whites in the stand mixer at high speed. When they become white and frothy, gradually add the sugar. The whites should be slightly whipped before adding sugar to avoid making them too heavy. Do not whip the egg whites to stiff peaks; stop just short of that point.
Gently fold the egg whites into the yolk and chocolate mixture, preferably in two additions, using a spatula or whisk. Add the sifted flour and fold from top to bottom until the batter is smooth and uniform.
Butter and flour an 18 cm (7 in) cake pan. Pour in the batter and level the surface. Bake in a preheated static oven at 170°C (338°F) for 35–40 minutes.
After baking, check doneness with a skewer. Let the cake cool completely before removing it from the pan. Once cooled, slice the cake horizontally into two layers with a serrated knife.
To fill the cake, spread about half of the apricot jam evenly on the bottom layer and then place the second layer on top. Spread additional jam on the top and sides for a smooth, glossy finish.
For the ganache, heat the cream in a small saucepan. At the first boil, remove from heat and add the chocolate, stirring with a whisk until smooth.
Place the cake on a wire rack and pour the ganache evenly over the top and sides, using a spatula to smooth it out. Let the ganache set in the refrigerator at 4°C (39°F) for about 20 minutes.
Serve your delicious Sacher Cake on a serving plate, optionally accompanied by whipped cream or fresh cream.