15 chocolate mini rolls, 12 halved down the middle, 3 left whole
cocoa powder, for dusting
Grease a 900g loaf tin with oil and line with a double layer of cling film. Put the coffee, sugar and 125ml water in a pan, and bring to the boil. When the sugar has dissolved, remove the syrup from the heat. Add the coffee liqueur and set aside to cool.
Whisk the double cream until it just holds its shape. Fold through the mascarpone, and then the coffee syrup. To assemble the terrine, press half the halved mini rolls into the tin, cut-side down, trimming them to fit. Tip half the cream into the terrine, then line the whole mini rolls down the middle. Top with the rest of the coffee cream and press the other half of the cut mini rolls into the cream, cut-side up. Wrap with the cling film and press down gently to push the top layer of rolls into the cream, then freeze.
Before serving, remove the terrine from the freezer and place in the fridge for 1 hr, then turn out onto a chilled serving dish. Dust heavily with cocoa powder before cutting into slices.