In a medium pan, saute mushrooms and onion in 3 1/2 tablespoons of the butter until just tender, about 5 minutes. Stir in the bread crumbs, Parmesan, salt and pepper.
Butter the bottom and sides of a 10 inch deep dish pie pan with remaining butter. Press mushroom mixture into pan evenly on bottom and sides. Sprinkle shredded cheese over the mushrooms.
In a blender, beat together cream cheese, eggs and hot pepper sauce until well incorporated. Stir in diced ham. Pour over the shredded cheese and bake 30 minutes or until set in center. Garnish with fresh chopped parsley.