Melt butter in a skillet. Sauté the garlic and dried tarragon for 2 minutes. Take half of the garlic butter and add it to the bread crumbs in a mixing bowl. Set aside to cool.

To the remaining garlic butter in the skillet, add the shallots and spinach, and cook 3 minutes, until the spinach wilts. Deglaze the pan with Pernod. Season with salt and pepper and hot sauce. Allow the mixture to cook for a few minutes.

To the bread crumbs, add the olive oil, Parmesan, and parsley, and season with salt and pepper to taste.

Using a kitchen towel, hold each oyster firmly. Insert an oyster knife in the small opening between the shells where the oyster is hinged. Gently pry open the oyster. Loosen the oyster from the shell by carefully running the knife below the oyster, trying to keep as much of the oyster liquor in place.

Top each oyster with 2 teaspoons of the spinach mixture. Sprinkle the spinach with the prepared bread crumbs.

Prepare the grill. Cook the oysters, shell side down, over direct high heat for 5–6 minutes. Use tongs to remove the oysters from the grill and serve immediately.