Bring the cream and the milk up to blood temperature in a saucepan over a medium heat

Add the lemongrass, remove from the heat and leave to cool

Bring the cream mixture back up to blood temperature over a medium heat

Whisk in the cream mixture a little at a time until incorporated

Pour the custard through a sieve back into the saucepan

Lower the heat and stir continuously with a wooden spoon until the custard thickens and coats the back of the spoon

Place 4 ramekins into a roasting tray

Pour the custard into the ramekins

Fill the roasting tray with warm water until the level is halfway up the ramekins

Bake for 1 hour

Remove the ramekins from the roasting tray and leave to cool

Place into the fridge until you are ready to serve them

Sprinkle demarara sugar over the top of the set custard

brûlée the sugar using a blowtorch or under the grill