Ingredients:
250 grams dark chocolate, chopped
3/4 cup all-purpose flour
2 teaspoons baking powder
1/2 teaspoon salt
1/2 cup butter, softened
1 cup sugar
4 eggs
5 tablespoons orange juice
1/2 cup water
1/3 cup whipping cream
1 tablespoon golden syrup
1/2 cup orange marmalade

Directions:
Preheat oven to 180°C (Gas mark 4). Grease and flour a 20cm square by 5cm deep baking pan; set aside.
Melt 100 grams of chocolate in a glass bowl over a pan of boiling water, ensuring that the bottom of the bowl doesn't touch the water, until chocolate just starts to melt. Remove from heat. Stir until smooth; cool. Stir together the flour, baking powder, baking soda, and salt; set aside.
In a large mixing bowl, beat the butter with an electric mixer on medium to high speed for 30 seconds. Add sugar; beat until combined. Add eggs, one at a time, beating well after each addition. Beat in chocolate and the 3 tablespoons orange juice. Add flour mixture and water alternately to egg mixture, beating on low speed after each addition just until combined. Pour batter into prepared pan.
Bake in preheated oven for about 35 minutes or until a wooden toothpick inserted near the center comes out clean. Cool cake on a wire rack for 10 minutes. Loosen edges of cake with a spatula. Invert onto wire rack. Remove the pan. Cool cake thoroughly on wire rack.
Meanwhile, combine whipping cream and golden syrup in a heavy small saucepan. Bring just to boiling, stirring constantly. Remove from heat. Stir in remaining chocolate, stirring until chocolate is melted and mixture is smooth. Cool to room temperature. Stir before using.
Split cake in half horizontally. Sprinkle each cut side with remaining orange juice. Place bottom half of cake, cut side up, on a platter; spread the marmalade evenly on top. Top with remaining cake layer, cut side down.
Frost the cake with the Bittersweet Chocolate Icing.