Wonderful Oyster Rockefeller Bread Pudding

WONDERFUL OYSTERS ROCKEFELLER BREAD PUDDING8 c. (1”) cubed French bread6 T. melted butter4 T. minced garlic, divided3 T. butter1 c. chopped fennel1 c. chopped onion½ c. chopped celery1 c. frozen chopped spinach, thawed and squeezed dry½ c. chopped fresh parsley2…