1. Preheat oven to 180°C. Apply a little butter on the inner side of a spring-bottom cake mould.

2. Crush the arrowroot biscuits into a bowl. Add 2 tbsps butter and mix well. Line the base of the cake mould with half of this mixture.

3. Cut the chocolate cake into small cubes and place in another bowl. Add condensed milk, cinnamon powder, almonds, pistachios and remaining butter and mix well.

4. Put this mixture into the cake mould over the biscuit layer and spread it evenly all over. Press lightly. Spread the remaining biscuit mixture over the cake and press lightly.

5. Keep the cake mould in the preheated oven and bake for 18-20 minutes. Remove the mould from the oven and carefully demould it.

6. Cut into wedges and serve hot with chocolate sauce.