In a large skillet, melt the butter over medium heat. Add the shallots, celery, green onions, and garlic, and cook until soft and translucent, about 5 minutes.
Add the spinach to the skillet and cook until wilted, about 2 minutes.
Remove the skillet from the heat and stir in the breadcrumbs, Parmesan cheese, and Pernod—season with salt and pepper to taste.
Spoon the mixture over the oysters on the half shell, dividing it evenly among them.
Place the oysters on a baking sheet and bake until the topping is golden brown and the oysters are cooked through, about 10 minutes.
Serve hot with lemon wedges on the side.
Notes
Enjoy your delicious and flavorful Oysters Rockefeller!