Preheat the oven to 170°C (340°F). Line the bottom of a cake tin with parchment paper, grease the sides, and dust with a little flour.

For the chocolate batter, melt the couverture over a double boiler and then let it cool slightly. Split the vanilla pod lengthwise and scrape out the seeds.

Separate the eggs, and beat the egg whites until stiff peaks form. Cream the soft butter with the sugar, vanilla seeds, and egg yolks until fluffy. Gradually add the melted chocolate. Sift the flour over the mixture and fold it in. Finally, gently fold in the beaten egg whites.

Pour the mixture into the cake tin, smooth the top, and bake in the middle of the oven for approximately 55 minutes.

Allow the cake to cool completely, then, according to preference, slice it once or twice horizontally. Warm the jam slightly, stir until smooth, and spread it on the cake layers. Reassemble the cake, spreading jam on the top and sides, allowing it to set.

For the glaze, put the sugar in a saucepan with 125 ml of water and boil for about 5 minutes over high heat. Let it cool slightly. Meanwhile, melt the chocolate over a double boiler, and gradually mix it with the sugar solution while stirring continuously until a smooth, thick glaze forms. Pour the entire lukewarm glaze over the cake's surface and quickly spread it with a palette knife. Let it dry afterward.