In a 12-inch frying pan over medium heat, melt a tablespoon of the butter and add the olive oil. Once the oil has come up to temperature, sear the mushroom caps until lightly browned on both sides. This should take about 2 minutes per side. Remove mushrooms from the pan and set aside on a separate plate. Season them with salt and pepper to taste.Into the same pan with the remaining oil and butter, add the shallot and garlic. Cook for a few minutes until the shallot has softened. Be sure to keep the mixture moving so the garlic does not burn. Add the Pernod and vermouth to the pan. Cook for a minute or two to evaporate some alcohol, remove the shallot and garlic mixture, and set aside in a separate bowl.Melt the remaining tablespoon of butter in the pan. Add the flour and whisk until fragrant. This should take about two minutes. Whisk in the milk making sure there are no lumps. Once the mixture starts to thicken, add the spinach and the garlic and shallot mixture. Check for seasoning. Add salt and pepper to taste.Now mix the parmesan and breadcrumbs together in a separate bowl. Turn your oven on broil. You are now ready to assemble the dish. Gather 12 ceramic soup spoons. Into each place 1 tablespoon of the spinach mixture, one large oyster mushroom cap, a tablespoon of the parmesan mixture, and a drizzle of olive oil. Broil for 2-4 minutes or until browned. Keep warm in a low oven until ready to serve. Serve with lemon slices and chopped parsley.