Step 1: Preheat the oven and prepare the oysters

• Preheat your oven to 450°F (230°C).
• Scrub the oysters under cold running water to remove any dirt or debris.
• Using an oyster knife, carefully shuck the oysters, discarding the top shell and loosening the oyster from the bottom shell. Arrange the shucked oysters on a baking sheet lined with rock salt or kosher salt to keep them steady.

Step 2: Prepare the Rockefeller topping

• In a saucepan, melt the butter over medium heat.
• Add the shallots and garlic, and sauté until softened, about 2-3 minutes.
• Stir in the chopped spinach and parsley, and cook until the spinach wilts, about 2 minutes.
• Remove the pan from the heat and stir in the bread crumbs, Parmesan cheese, salt, pepper, and nutmeg until well combined. If using Pernod, stir it in at this stage.

Step 3: Top the oysters and bake

• Spoon a generous amount of the Rockefeller topping onto each oyster, covering it completely.
• Place the baking sheet in the preheated oven and bake for 8-10 minutes, or until the topping is golden brown and bubbly.

Step 4: Serve and enjoy

• Carefully transfer the hot oysters Rockefeller to a serving platter.
• Garnish with additional chopped parsley, if desired, and serve immediately, while still hot and bubbling.