1. Cook the chestnuts in boiling water until they are tender, then remove the shells and skins.
2. Sieve the chestnuts to make a puree.
3. Cream together the butter and sugar, then beat in the chestnut puree.
4. Melt the chocolate gently in a heatproof basin over a pan of hot water.
5. Add to the chestnut mixture and blend well.
6. Turn into a lightly oiled and bottom-lined tin.
7. Keep in a cool place until ready to serve.
8. Serve with fresh cream and fruit.