Preheat the oven to 150°C and butter a 2-litre pudding basin.
Gently heat cream and white chocolate in a saucepan until melted.
Whisk egg yolks, Irish cream liqueur, and sugar in a bowl until pale.
Pour the warm cream mixture into the eggs, stir vigorously, and transfer to the pudding dish.
Place the dish in a roasting tin and fill the tin with boiling water 3cm up the sides.
Bake in the centre of the oven for 40-45 minutes until almost set.
Cool the pudding for one hour, then chill in the fridge overnight.
Dissolve sugar in 4 tablespoons of water over medium heat.
Boil without stirring for 5-7 minutes until golden-brown.
Remove the caramel from heat immediately once it reaches a maple syrup colour.
Pour caramel over an oiled metal spoon onto the custard and cool for 15 minutes.
Preheat the oven to 200°C and line baking trays with parchment.
Cream butter and icing sugar, then mix in zest, spices, egg whites, and flour.
Pipe 6cm strips of the mixture onto the baking trays.
Bake for 6-8 minutes until edges are golden and leave to cool.
Serve the custard with the biscuits on the side.