These incredibly rich and creamy coffee-flavoured variations on the classic brûlée have a more unusual method for creating an extra-crunchy topping. Here, the caster sugar is cooked to a caramel and allowed to set, then broken into shards. These are blitzed to a fine sand in a food processor before being sprinkled onto the custards and melted under the grill.
Heat the oven to 170°C/325°F/Gas 3. Put the egg yolks into a large heatproof bowl, add the sugar and vanilla extract, and mix with a wire whisk until thoroughly combined.
Pour both creams into a medium pan and heat until scalding hot. Remove the pan from the heat, add the instant coffee and stir until dissolved. Leave to cool for a couple of minutes, then pour the coffee cream slowly onto the egg yolks, whisking constantly. Strain the custard into a jug, then pour into the buttered ramekins, dividing equally.
Set the ramekins in the roasting tin and pour hot water into the tin to come halfway up the side of the ramekins. Bake in the heated oven for 25–30 minutes until the custards are just set. Remove the ramekins from the roasting tin and leave to cool. Once cold, cover the ramekins with clingfilm and chill overnight, or for up to 2 days.
To make the caramel topping, put the sugar in a stainless-steel pan and add a little water to dampen. Set over a medium heat and stir gently until the sugar has completely melted. Turn up the heat to high and cook, without stirring, until the sugar syrup has turned to a pale straw-coloured caramel. Pour the caramel onto the lined baking sheet and leave until cold and hard.
Break up the caramel into chunks, then blitz in a food processor to make a fine sandy sugar. Sprinkle the caramel sugar evenly over the chilled custards. Place them side by side on a grill pan or baking sheet.
Heat the grill to its highest setting. Slide the pan of ramekins under the grill, as close to the heat as possible, and grill for 4–5 minutes until the sugar has melted and turned to a rich caramel. Be careful not to burn the sugar or leave the ramekins under the grill for too long as you risk re-heating and overcooking the soft-set custard. Cool briefly until the caramel has set, then serve as soon as possible.