Hydrate the mushrooms in warm water for 15 minutes, Boil in water for 5 minutes, take out the mushrooms and set aside water for other uses (soups, sauces)

Caramelize the onions in a pan with butter and deglaze with port, add the thyme and leave to reduce completely

Put all ingredients except the mushrooms in a food processor and add 120g of butter and cream

Pour into a ziplock bag and refrigerate to harden

Stuff the mushrooms entirely or half with the mixture

Reheat over low heat 5 minutes before serving