Generously feeds 5-6
1 medium onion
500g chestnut mushrooms
~150g drained tinned chestnuts (I used Clément Faugier Marrons Entiers)
Chop mushrooms & onion. Fry onion in a little olive oil (fry-light will do), caramelise with a bit of wine vinegar, add crushed garlic, add mushrooms, cook over a slow heat until mushrooms are done. Grate in a little nutmeg.
Put all ingredients into a blender, and blend until smooth. Chill before serving.