1. In a saucepan reduce the beer down to ~3.5 oz. Remove from heat and set aside.
2. In a bowel beat the sugar, eggs, yolks, cocoa powder, and vanilla together until smooth.
3. In a large saucepan bring the cream and milk to boil.
4. Slowly add the cream to the egg mixture .25 cup at a time while you beat the egg mixture rapidly and constantly. Make sure you keep beating the mixture as you add the hot liquid. Once you add 1.5 cups of cream to the eggs they should be cooked (you are trying to avoid making scrambled eggs by slowly heating them). Add the now hot egg mixture back to the pan.
5. Stir in the reduced stout to the rest of the mixture.
6. Cool to room temp and then fridge temp. Follow the ice cream makerís instructions to finish freezing. Add the chopped chocolate at the end of the freezing.