Preheat the oven to 150 C / 300 F / 130 FAN / Gas 2.
Separate the eggs and place the yolks in a mixing bowl with the caster sugar.
Whisk for 2 minutes, until the mixture is pale and frothy.
Blend the espresso powder with hot water from a recently boiled kettle and leave to cool.
Place the cream in a saucepan over a low to medium heat. Bring to simmer then remove from the heat and cool.
Whisk a very small amount of cream into the egg yolks, then gradually pour in the rest, whisking all the time.
Stir in the coffee.
Fill the ramekins with the mixture and place in a deep sided roasting tray.
Pour in hot water from a kettle so that it comes halfway up the sides.
Bake ramekins for an hour and shallow dishes for 30 minutes, or until the custard is just set.
Remove from the water bath, leave to cool then refrigerate for an hour.
For the topping, spread a layer of sugar over the baked custard.
Use a blow torch to caramelise the sugar. Alternatively, place under a very hot grill, watching constantly.
The topping will harden in a few minutes, but it's best to put the desserts in the fridge for a few minutes before serving.