• 24 oysters, shucked, with juice retained
• 2 tablespoons butter
• 2 tablespoons water
• 2 leeks, white and pale green parts only, thoroughly washed and sliced
• 2/3 cup cream
• Salt and freshly ground black pepper
• 3/4 cup (1 1/4 sticks) butter
• 1/2 cup Guinness
• 3 egg yolks
• Juice of 1/2 lemon
Over a small bowl, shuck oysters, strain and reserve the liquid and the shells.
Combine the butter and water and cook over medium heat until butter has melted. Add the leeks and cook until slightly tender, 3 to 5 minutes. Add the cream and reduce until it thickens slightly, stirring continuously, 3 to 5 minutes. Season with salt and pepper and keep warm in a bowl over hot water.
In a small saucepan over low heat, melt the butter. In another saucepan over medium heat, combine the reserved oyster liquid and Guinness and bring to a boil. Cook until reduced to about 2 tablespoons. Transfer the mixture to a food processor or blender. With the motor running, add the egg yolks and lemon juice, then slowly drizzle in the melted butter and process until thickened.
Preheat the broiler. Place the reserved oyster shells on a baking sheet. Divide the creamed leeks evenly into the shells and top with an oyster. Spoon the Guinness hollandaise sauce over each and place under the broiler until the sauce is browned and bubbling. Serve 4 oysters per person.