1) Puree bread crumbs, butter, spinach, spring onion, celery, garlic, onions, Pernod, vinegar, thyme, anise, salt, and pepper in a food processor. 2) Pour into a pastry bag with a ½" fluted tip and refrigerate for an hour until cold. 3) Heat grill to high. 4) Pipe filling over oysters. 5) Grill until tops are browned, about 4 minutes.