In a food processor or by hand, finely chop the garlic and 1 pound of the mushrooms. Cut the remaining ½ pound mushrooms into thin slices. In a 4-quart saucepan, heat 2 tablespoons of the oil and saute the garlic and mushrooms for 3 minutes. Remove from the pan and set aside. Add the remaining 2 tablespoons oil to the pan and saute the bread crumbs. Add the mushroom mixture to the crumbs, stir in the parsley, and saute for 5 minutes. Add the broth and simmer, stirring frequently, for about 15 minutes. Season with salt and pepper to taste, Tabasco, and sherry to taste (if using).