- Mix chestnut purée and sour cream using a food processor or mixer.
- Whisk egg yolks and vanilla into chestnut purée and sour cream mixture.
- Bring heavy whipping cream to a boil.
- Whisk in chocolate. Continue to boil until smooth (approximately 2 minutes).
- Temper chocolate and sour cream mixtures by slowly combining hot mixture to cool chestnut mixture.
- Pour into cups or bowls and chill until it sets.