1. Melt butter in a heavy-based saucepan, add onion, leek and celery and cook, stirring occasionally, over low heat for 8-10 minutes or until softened.
2. Add 430g chestnuts, potato and stock and season to taste with sea salt and cracked black pepper. Bring to the boil, then reduce heat and simmer, partially covered, for 20 minutes or until chestnuts are soft.
3. Process chestnut mixture in a food processor until smooth, then strain through a sieve into the same pan.
4. Add cream and return mixture to the boil, stirring frequently to prevent soup from burning. Add lemon juice and adjust seasoning to taste.
5. For parsley oil, add parsley leave to a large saucepan of boiling water for 10 seconds, drain and refresh in ice-cold water.
6. Squeeze dry in a kitchen towel to remove as much moisture as possible, puree in a food processor with the oil for 2 minutes or until smooth, then strain through a fine sieve.
7. Ladle soup into bowls, drizzle with parsley oil
Another recipe by Michael Ryan