Preheat oven to 200 degrees C. Drain escargots; rinse in cold water and drain again.
In a mixing bowl combine the butter, garlic, spring onion, parsley, pepper, nutmeg and wine. Mix thoroughly. Place 1 teaspoon of butter mixture into each vol-au-vent shell. Top each with 1 escargot, cover with another teaspoon of butter mixture and place mushroom cap on top.
Arrange pastry shells on a baking tray. Bake in preheated oven for 8 to 10 minutes or until golden brown.