This recipe for chocolate slices was chosen from Warm Bread and Honey Cake by Gaitru Pagrach-Chandra. She writes "This is the cake I came up with after my Sacher-eating experiences in Vienna. It stands or falls with the quality of the chocolate, and every chocolate has its own unique flavour characteristics. I generally use Belgian Callebaut, a standard ingredient in my kitchen. We like it best with the chocolate slightly softened, so I usually pop the portions into the microwave for a few (very few!) seconds.
"These slices are quick and simple to make and can be assembled and served as soon as the cake is cool enough to handle."
250g dark chocolate, chopped
190g butter, cut into cubes
3 tbsp rum or brandy
190g granulated sugar
5 eggs
125g plain flour
1 tsp baking powder
1/4 tsp salt
About 140g sieved apricot jam
Lightly sweetened whipped cream, for serving
Swiss roll tin 38x25x2.5cm
Method
Put the chocolate and butter in the top part of a double boiler. If you don't have a double boiler, choose a heatproof bowl that fist snugly on top pf a saucepan. Put enough water in the bottom of the double boiler/saucepan so that the pan or bowl holding the chocolate will be just clear of the water. Bring the water to the boil, then turn the heat low and put the pan/bowl with the chocolate and butter on top of this. Leave to melt, stirring from time to time. Remove from the heat and stir in the rum. Set aside.
Grease the Swiss roll tin and line with parchment. Preheat the oven to 160C/325F.
Use an electric mixer to whisk the sugar and eggs together until the mixture is pale yellow and so thick it falls off the whisk in a thick ribbon rather than a stream. Sift the flour, baking powder and salt together. Fold the chocolate mixture into the eggs, then fold in the flour carefully. Don't overwork the mixture. Stop as soon as there are no more pale streaks left. Transfer teh mixture to the prepared tin and level the top with a spatula. Hold the tin about 15cm above the work surface then let it drop so it falls with a gentle thud - right side up of course!. If you are reluctant to do this, don't bother with this step, but your cake will have a slightly spongier, more open texture. The slight impact allows some of the larger air bubbles to burst.
Bake in the oven for about 20 minutes. A skewer stuck into the centre should come out fairly clean or with a few crumbs, but the cake should be just cooked and not allowed to dry out.
Leave to cool in the tin for about 5 minutes, then loosen the edges with a small spatula. Turn out very carefully onto a cooling rack. Be gentle - it's fragile. The best way is to invert a rack over the cake and then quickly re-invert the cake and the rack together so that the cake is now on the rack. Remove the baking paper and leave to cool.
When cool, cut horizontally into 3 equal rectangles. Put one layer on a serving plate or board and spread with half of the apricot jam. Sandwich the rest of the cake in the same way. You might like to slip a large piece of cardboard or a think sheet of metal like a loose pan base under each rectangle as you move each later; they break easily.
Serve fresh, at room temperature with a dollop of lightly sweetened whipped cream on the side. You can keep it for a day or two, well wrapped, in the refrigerator, but bring to room temperature before serving.

Buy Warm Bread and Honey Cake from Anova Books
Gaitri writes "This cake is easily adapted to suit a gluten-free diet. Simply substitute very finely ground nuts such as almonds or hazelnuts for the flour and use a gluten-free baking powder. It will be denser than the flour version."
Read more about British chocolate - recipes and more - in Dipping into British Chocolate
Read more about traditional breads and baking, visit Our Daily Bread