Lazy Cake (Chocolate Biscuit Cake)

Prepare the Chocolate Sauce

1. Melt the butter in a saucepan, and add the milk, cacao powder, and icing sugar. 
2. Give them a good stir, place the pan on medium-low heat, and bring it to a boil.
3. Remove the pan from the heat and add the chocolate pieces.
4. When the chocolate pieces melt, give the mixture a good stir until the sauce is nice and shiny, and all the chocolate is incorporated.
5. Let the chocolate sauce cool down for 10 minutes while preparing the biscuits and lining the loaf pan with a cling film or parchment paper.

Prepare the Cake

1. Line a 23 cm (9") loaf pan with cling film or parchment paper, leaving an overhang to cover the cake later. This step is necessary to avoid the cake from sticking to the pan when you invert it.
2. Lightly toast the walnuts in a 160° C (320° F) preheated oven for 10 minutes.
3. Break the biscuits into chunky pieces in a large bowl and add the roughly chopped walnuts.
4. Pour in the chocolate sauce and give them a gentle stir, making sure all is combined.
5. Transfer the mixture to the loaf pan and press it gently, making sure that the biscuits are firmly packed without any gaps.
6. Cover the top of the cake with overhanging cling film (or parchment paper), and place it in a freezer.
7. Freeze the cake for a minimum of 3 hours, remove the cling film and transfer it to a serving plate.
8. Alternatively, if you're not serving it on the same day, you can place the cake in the fridge overnight.
9. Garnish with ground pistachio and/or desiccated coconut, slice and serve.