Whisk together the eggs, egg yolks and condensed milk in a bowl until just combined. Gradually whisk in the coffee until blended.
Strain the mixture through a sieve, then pour into 6 small 125 ml (4 fl oz) greased coffee cups. Transfer the cups to a roasting tin. Pour enough hot water into the tin to come halfway up the sides of the cups, then cook in a preheated oven, 160°C (325°F), Gas Mark 3, for 30 minutes until just set.
Lift the cups out of the water, leave to cool on a wire rack, then transfer to the refrigerator and chill for 4–5 hours.
Whip the cream until it forms soft swirls, when ready to serve. Spoon the cream over the top of the desserts, dust with a little sifted cocoa powder and serve with the chocolate wafer biscuits.