Step 1: Preheat Oven ; Preheat oven to 350°F (175°C). Grease a 9-inch (23 cm) springform pan and line the bottom with parchment paper.

Step 2: Melt Chocolate : Melt 7 oz of dark chocolate in a heatproof bowl over a pan of simmering water (double boiler). Set aside to cool slightly.

Step 3: Prepare Batter : In a large bowl, cream the softened butter and sugar until light and fluffy. Beat in egg yolks one at a time, then add vanilla extract and melted chocolate.

Step 4: Whip Egg Whites : In a separate clean bowl, beat the egg whites with a pinch of salt until stiff peaks form. Gently fold the egg whites into the chocolate mixture in batches, being careful not to deflate the batter.

Step 5: Incorporate Flour : Sift the flour over the batter and fold gently until just combined.

Step 6: Bake the Cake : Pour the batter into the prepared pan and smooth the top.

Bake for 50–60 minutes, or until a toothpick inserted in the center comes out clean. Let the cake cool in the pan for 10 minutes, then remove from pan and cool completely on a wire rack.

Step 7: Prepare Apricot Filling :Warm apricot jam with lemon juice in a small saucepan or microwave. Strain if needed.

Step 8: Slice and Fill Cake : Carefully slice the cake horizontally into two layers. Spread the apricot jam evenly over the bottom layer, then place the top layer back.

Step 9: Make Chocolate Glaze : Heat heavy cream until simmering. Pour over chopped chocolate and stir until smooth. Allow glaze to cool slightly before pouring over the cake, smoothing the sides with a spatula.

Step 10: Set and Serve : Let the glaze set for at least 30 minutes at room temperature. Slice and serve with lightly sweetened whipped cream if desired.