Place cream, cardamom, coffee, coconut and half the sugar in a saucepan and bring gently to the boil. Remove from heat, cover and leave to infuse for 10 minutes. Lightly whisk yolks with the remaining sugar for 20 seconds, then slowly pour in the hot cream mixing well. Strain into a clean jug.
Divide mixture between the ramekins and carefully place in a roasting pan with enough hot water to come two-thirds up the sides.
Once cooked, turn the oven off and very carefully take the bain-marie from the oven (the roasting dish is full of very hot water, so be careful). Remove ramekins from the bain-marie and cool on a wire rack for 30 minutes. Refrigerate, covered, for 4 or more hours until they have set firm.
Just before serving, sprinkle demerara sugar in a thin layer on top of each brûlée. Place under a very hot grill, or use a cook’s blowtorch, until a thin layer of caramel forms. Keep an eye on them as they will go from sugar to burnt toffee quite quickly. Stand 1 minute before serving, as the toffee will burn your lips.