Put a ½-inch layer of the rock salt in 2 large jelly-roll pans.

Cook the bacon in a large skillet over medium 4 to 6 minutes or until crisp; drain, reserving drippings in skillet.

Add the butter and the flour to hot drippings; cook, stirring constantly, 3 to 5 minutes or until golden brown. Add the spinach and the next 5 ingredients. Bring to a simmer. Cook, stirring occasionally, 10 minutes or until very thick. Remove from heat. Stir in the absinthe and bacon, and add table salt to taste

Preheat the broiler with oven rack 6 inches from heat. Arrange 18 oysters on salt in prepared pans; top with the spinach mixture. Broil 4 to 6 minutes or until lightly browned.