For the mushroom cooking liquid, place a full handful of dried mushrooms, (preferably porcini) into a small saucepan. In a separate pot boil some water.
Pour enough boiling water over the mushrooms just to cover. Cover the mushrooms with a lid and allow them to steep for 20-30 minutes.
Strain the liquid through cheesecloth. Reserve 4 tablespoons for the recipe and the remainder of the liquid and mushrooms for another use.
Combine the mushroom liquid, stock and veloute sauce in a pot. Bring to a boil and reduce by half.
Add the heavy cream, butter, salt and pepper and reduce to desired thickness.