Dark and stormy crème brûlée

Method

1. Put the ginger beer, grated ginger, 3 tbsp of the rum and 30g of the caster sugar in a small pan over a medium-high heat. Simmer for about 10 minutes until reduced to around 60ml syrup. Strain into a small bowl, stir in the remaining rum, the bitters and lime zest, then set aside to cool.
2. Heat the oven to 120°C/100°C fan/gas ½. Pour the milk and cream into a large saucepan and bring to a simmer. Meanwhile, in a large heatproof bowl, whisk together the egg yolks, the remaining caster sugar and the reduced ginger syrup, then slowly pour the hot cream mixture over, whisking all the time, until combined. Strain the mixture through a sieve into the baking dish and transfer to a large roasting tray.
3. Transfer the roasting tray to the middle shelf of the oven and fill halfway up the sides of the baking dish with hot water from a just-boiled kettle. Bake for 35-40 min until just set but with a good wobble. Cool completely, then transfer to the fridge to chill and set (see Make Ahead below).
4. To serve, sprinkle the demerara sugar over the surface of the crème brûlée and use a cook’s blow torch to gently melt and caramelise the sugar to a crisp layer. Sprinkle with a little extra lime zest to serve.