Put the raspberries, sugar and lemon juice in a small pan on a low heat. Simmer for 10-12 minutes, stirring every so often, until the raspberries break down and make a jam (it will be quite runny compared to normal jam). Sieve into a bowl to remove the seeds, and leave to cool.
Crisp up the croissants in the oven if you wish, but let them cool before filling. Split the croissants horizontally down one side to make a pocket. Add the scoops of ice cream, a generous spoonful of the jam, the peanut butter, and some of your favourite chocolate crumbs. Squidge everything together and dive in! You can serve some of the extra jam on the side, for dipping.