Open the oysters and discard the top shell and arranging the oysters on a baking sheet.
Heat butter and olive oil in a sauté pan and add the shallots, fennel, garlic and saute it over medium low heat for about 5 minutes.
Add the Pernod or Absinthe, salt and pepper while stirring the mixture continuously.
Add the spinach to pan with a little butter and cook for about 2 minutes, drain well, season and divide the spinach mixture evenly among 12 oysters and top each oyster with 1 tsp grated Cheese. Bake the oysters in a preheated 375 degrees F oven for 5 minutes.