For the ice cream, melt the sugar in the same way, and once it is caramelised, add the butter and cream and re-melt everything together. pour this mixture into the egg yolks and whisk well. Add the milk and then strain the lot back into a clean pan. Cook gently over a medium heat, stirring all the time until the mixture begins to thicken a little. Don’t overcook it or it will scramble. Stir in the peanut butter. Tip into an ice-cream machine or freezerproof box and churn or freeze until the mixture is almost set. If you use a box then beat the mixture vigorously once or twice while it firms up.