Preparing the crème anglaise: Bring the milk to the boil in a saucepan. In a mixing bowl, beat the egg yolks with the sugar until pale and creamy, then add the ristretto. Add the boiled milk, stirring continuously. Put the mixture into the saucepan and cook, stirring with a spatula until the spatula becomes coated. The cream must not boil. Set aside in the refrigerator.
Preparing the mocha caramel: In a saucepan, cook the sugar with 2 tbsp of water until you obtain a good caramel. Stop the caramel from cooking with the coffee and allow to reduce. Set to one side.
Preparing the floating islands: in a mixing bowl, whisk the egg whites into very firm peaks with a pinch of salt and the sugar. Fill four hemispherical bowls with the whites, cover with cling film and steam cook for around 5 minutes. Leave to cool and remove from the moulds.
Assembly: coarsely chop the nuts, sprinkle with icing sugar and caramelise under the grill. Pour the crème anglaise into a bowl or glass, carefully place the floating island on top, sprinkle with chopped nuts and pour the mocha caramel over the top. Serve well chilled.