Paprika Oven method: (27 minutes cooking time) Melt butter in small skillet over medium heat, about 1 minute, add onion, green pepper, and celery. Saute' until tender, about 6 minutes. Combine onion mixture, cream cheese, bread crumbs, salt, pepper, lemon juice, and worcestershire sauce in bowl. Mix well. Fill mushroom caps heaping full of mixture. Place in greased 20 cm square baking pan. Sprinkle with paprika. Bake in 350-degree oven for 20 minutes. Serve with coctail picks.