Preheat oven to 160ºC (320ºF). Cut the pastry into 12 x 10cm rounds. Cut a slit halfway through each round (this will make it easier to mould into tart shells). Line the bases of 12 x ½ cup-capacity (125ml) lightly greased muffin tins with the pastry. Prick the bases with a fork and line with non-stick baking paper. Fill with pastry weights and bake for 15 minutes. Remove the paper and weights and bake for a further 5–8 minutes or until golden and crisp. Allow to cool on a wire rack.
Place the milk, chocolate and vanilla in saucepan over medium heat and stir until melted. Bring to the boil and remove from heat. Place the egg yolks and sugar in a bowl and whisk until pale and creamy. Add the cornflour and whisk to combine. Gradually pour in the hot milk mixture, whisking continuously. Return to saucepan and cook over medium heat, whisking continuously, for 1–2 minutes or until slightly thickened. Stir through the coffee liqueur. Pour mixture into the tart shells and refrigerate for 4 hours or until set. Sprinkle tarts with caster sugar. Use a blowtorch to caramelise the sugar. Top with chocolate shavings and double cream to serve. Makes 12.