Place the dried mushrooms in small bowl and add one cup of water, allow to set.

Take a damp cloth or paper towel and clean any dirt off of the fresh mushrooms. Cut the mushrooms into uniform size and set aside. (If only using fresh mushrooms, add an extra cup.)

Mince the garlic and cut the onion to a small dice. Place the olive oil in a large skillet and sauté the garlic and onion until translucent.

Add two tablespoons of butter or olive oil to the skillet and then add the fresh mushrooms to the onion mixture. Cook until the mushroom juice has evaporated, stir occasionally.

Remove the dried mushrooms from the water and squeeze the excess water out of them. Add the remaining tablespoon of butter or olive oil to the skillet and the rehydrated mushrooms. Cook until the liquid has evaporated, stirring occasionally. (Skip this step if not using dried mushrooms.)

Add the sherry and continue cooking until it has dried up. Add the thyme leaves and mushroom water (used to soak the mushrooms in). If you did not use any dried mushrooms, add one cup of vegetable, chicken, or beef broth.

Cook down until the mushroom water or broth has all evaporated. Turn off the heat and add the heavy cream. (Omit cream for vegan options.)