1st step: In a saucepan, heat the milk to boiling point with cocoa powder. Stop the cooking process and exit the saucepan from the fire. Book. 2nd step: In a bowl, mix the egg yolks with the sugar until the mixture whitens. Pour then gradually the boiling milk, stirring constantly. Replace the preparation in a saucepan and gently heat to simmer, stirring constantly with a wooden spoon. The mixture is ready when the cream ribbon the back of a spoon. To check, place your finger on the back of a spoon: the trace that fact your finger must remain clear, the cream must not join. 3rd step: When the cream chocolate english pad the back of a spoon, remove the pan from the fire and made the cool down by plunging your saucepan in a container a little bit more filled with water and ice cubes. Begin to slowly rotate in order to smoke the custard. Add at the same time black chocolate cut in song. While stirring gradually, you'll melt the chocolate at the same time as the cream cools. Once done, let cool in the refrigerator several hours, or even a day. Finalization: Cut the white chocolate into small pieces. With ice cream maker: made powerhouse during 40 minutes and then pour in a tray from the freezer, leave taken during 12 hours before enjoying. Add the white chocolate at the end of about ten minutes. Without ice cream maker: Add the white chocolate and pour the mixture into a tray from the freezer. During the first hour, return every 10 minutes and stir or blend with a hand blender. Let then take during 12 hours before enjoying.