Preheat the oven to 450ºF. Line a baking sheet with parchment paper or waxed paper.
Heat the olive oil in a medium-size sauté pan over medium heat. Add the shallots, garlic, and leeks and season with salt and pepper. Cook, stirring, for 1 to 2 minutes. Add the wine and cook until the leeks are tender, another 2 to 3 minutes. Remove from the heat and set aside.
Heat a small skillet over medium heat. Add the tasso and fry until crispy, 4 to 6 minutes. Drain on paper towels. Reserve the rendered fat in the skillet.
Prepare the bottom of a double boiler with water and bring to a gentle boil over medium heat. Combine the egg yolks and lemon juice in a stainless steel mixing bowl and season with salt and pepper. Place the bowl over the boiling water and whisk until the yolks are thick and ribbonlike, 3 to 4 minutes. Whisk the melted butter and reserved tasso fat into the egg mixture in a steady stream. Season with salt and pepper and continue whisking until the mixture thickens again. Fold in the tasso. Keep warm.
Arrange the oyster shells on the baking sheet.
Season the bread crumbs with Essence. Season the oysters with Essence. Dredge them in the bread crumbs, coating each one evenly. Place a spoonful of the leek mixture in the center of each oyster shell. Lay an oyster on top of the leek mixture. Sprinkle them with the remaining bread crumbs. Bake until the tops of the oysters are golden brown, 4 to 6 minutes.
To serve, drizzle the oysters with the hollandaise sauce and sprinkle with the cheese and parsley.
Yield: 4 appetizer servings