Preheat the oven to 180 degrees Celsius.
Melt the butter in a heavy-bottomed saucepan. When the butter has almost melted, add the chocolate. Once the chocolate is soft, take the pan off the heat. Mix the butter and chocolate until uniform. Fold the cherry sauce into the chocolate mixture.
Whisk the egg yolks and cane sugar until light and fluffy. Fold into the chocolate mixture.
Sift flour and baking powder into the chocolate mixture and fold gently into the dough.
Whisk the egg whites and fold into the dough.
Line a round cake tin (approx. 20 cm diam.) with baking paper. Pour the dough into the tin. Bake the cake for approx. 35 minutes and let it cool for approx. 10 minutes in the tin. Put the cake in the freezer for around 2 hours.
Take the cake out of the freezer and remove any crumbs or similar that make the surface uneven. Finely chop 150 g of chocolate. Bring glucose syrup and cream to the boil. When the cream mixture is still hot, pour it over the chocolate. Stir with a rubber spatula until the chocolate mixture is uniform.
Pour the chocolate mixture into a small, high-sided bowl. Place the hand blender carefully in the bowl at an angle in order to prevent air bubbles being formed. Hold the hand blender at the bottom of the bowl and mix until the mixture is completely smooth. Carefully remove the hand blender.
Place the cake on a griddle with the edge of the cake protruding slightly (which makes it easier to transfer onto a serving dish). Place a baking tray with baking paper underneath.
Pour the chocolate over the cake from the centre. Work outwards until the entire cake is covered in chocolate.
Put the cake in the fridge for approx. 3 hours until the chocolate has set and the cake has thawed fully.
Finish with roughly chopped pistachio nuts sprinkled onto the cake.