Cut the butter into small pieces and soften it in a bowl at room temperature. Chop the chocolate and put it in a bowl.
Heat 25 cl of cream. Pour it over the chocolate and then add the butter. Leave to rest for 2 min before blending with a spatula.
In another container, mix the egg yolks, sugar and cocoa. Mix with the chocolate preparation and then with the remaining whipping cream. Pour into the pots.
Fill the base of the appliance with water up to the max level. Cook for 30 min in dairy dessert mode.
Leave to cool and then refrigerate before serving.