To make the pastry: Combine flour, sugar, salt and cocoa. Rub in the butter, add cold water and knead the dough until smooth and all the ingredients are well combined.
Line a tart tin with the dough. Prick the pastry in several places with a fork and leave to chill until the oven is preheated.
Preheat oven to 180 C / Gas 4. Bake for around 15 to 20 minutes.
Mix 5 tablespoons of instant coffee granules with 50ml boiling water. Set aside to cool. Mix in Amaretto and sprinkle the syrup over the baked crust.
Using an electric mixer, mix the mascarpone with milk and sugar.
Whip the cream to form stiff peaks and fold gently into the mascarpone. Spoon cream on top of the cooled pastry base; sieve cocoa (and/or grated dark chocolate) all over the top for a pretty presentation.