Preparation time: 1/2 hour. Preheat oven to 375?. Wash and remove stems from Mushrooms. Save the stems. Chop up the stems into small pieces. Put the chopped up stems and chopped shallots or leeks in a small saute pan and saute them with 2 tablespoons of the butter until the shallots are soft. Remove from heat and add bread crumbs, walnuts, parmesan cheese and white wine - mix thoroughly. Stuff mushroom caps with this mixture. Drizzle the top of mushrooms with 4 tablespoons of melted butter. Bake at 375? for 15 minutes. Serve hot. Everybody loves these - AND they are so fast and easy to make!