Preheat the oven to 170°C. Line the bottom of a springform pan with baking paper, grease the sides, and dust them lightly with flour.

Melt the couverture chocolate over simmering water and set it aside to cool slightly.

Slice the vanilla pod lengthwise and scrape out the seeds. Using a hand mixer with whisks, beat the softened butter with the powdered sugar and vanilla seeds until bubbles form.

Separate the eggs. Add the egg yolks one at a time to the butter mixture, whisking in between. Gradually pour in the melted couverture chocolate. In a separate bowl, beat the egg whites with the caster sugar until stiff peaks form. Gently fold the egg whites into the butter and chocolate mixture. Sift the flour over the mixture and fold it in as well.

Pour the batter into the springform pan, smooth the top, and bake on the middle rack for 10–15 minutes, leaving the oven door slightly ajar. Then, close the oven and bake for about 50 minutes. The cake is done when it springs back slightly to the touch.

Once baked, remove the cake from the oven, loosen the sides of the springform pan, and carefully transfer the cake onto a cooling rack lined with baking paper. Let it cool for about 20 minutes. Peel off the baking paper, flip the cake over, and allow it to cool completely on the rack.

Cut the cake in half horizontally. Gently heat the jam and stir until smooth. Brush the jam over the top of both cake halves, then place them on top of each other. Brush the sides with jam as well.

For the glaze, place the caster sugar and 125 ml of water in a saucepan and bring to a boil. Let it simmer for about 5 minutes, then remove from the heat and allow it to cool slightly. Coarsely chop the couverture chocolate, adding it to the syrup bit by bit. Stir until it thickens into a smooth glaze.