Gratin d’ananas au Rhum

• ½ lb. sugar
• 4 egg yolks from large eggs
• 2 whole large eggs

Make a thick crème pâtissière: place the sugar and egg yolks in a heavy saucepan and beat until the mixture is pale yellow and forms a ribbon. Beat in the 2 whole eggs, then the flour. Place over very low heat and cook, stirring until the mixture is lukewarm. Meanwhile bring the milk to the boil. Pour it into the egg mixture, stirring vigorously with a wire whisk. Continue to cook stirring, for