Prepare the fresh shitake mushrooms by cleaning with a dry towel and then breaking off the stems at the base of the cap. Discard stems.
Mix 2 tablespoons olive oil, 1 tablespoon Worcestershire sauce and salt and pepper to taste in an ovenproof baking dish.
Toss the mushroom caps in this mixture to coat and cover the dish with aluminum foil and roast for 15 minutes.
While mushrooms are roasting, prepare spinach mixture for topping.
Melt 1 tablespoon of butter in a sauté pan, and then add about a pound of fresh spinach leaves that have been washed and patted dry. Sauté just long enough to wilt, about 1-2 minutes, and then remove from heat.
Add 1 tablespoon of white wine, 2 tablespoons of finely chopped fresh garlic, and the juice of half a lemon and salt and pepper to taste. Toss.
When mushrooms are done, place them cap side down on an ovenproof plate. Top each with a heaping spoonful of the spinach mixture and then top with a generous sprinkling of Panko (Japanese-style breadcrumbs).
Drizzle with melted butter and broil until golden brown.