Balthazar's Cream Of Mushroom Soup

Ingredients

• 1 ounce dried mushrooms (porcini, morels, or shitakes)
• 1/2 cup olive oil
• 2 sprigs of rosemary
• 4 sprigs of sage
• 1 large yellow onion, peeled and thinly sliced
• 3 garlic cloves, peeled and thinly sliced
• 1 1/2 teaspoons salt
• 1/4 tsp freshly ground white pepper
• 1 pound white button mushrooms, cleaned and thinly sliced
• 1 pound shitake mushrooms stemmed, cleaned and thinly sliced
• 6 cups chicken stock or water
• 1 cup heavy cream
• 2 tablespoons unsalted butter