In a 5- to 6-quart pan over high heat, stir spinach until wilted, about 5 minutes. Drain, saving liquid. Purée about half the spinach in a food processor or blender.
Return reserved spinach liquid to pan and add cream, 1/2 teaspoon nutmeg, and 1 tablespoon Pernod. Boil over high heat until mixture is reduced to about 1/2 cup, about 10 minutes. Stir in puréed and whole spinach and additional nutmeg and Pernod to taste; stir until bubbling. Season to taste with salt and pepper.