Cook linguine until al dente, about 8 minutes. While pasta cooks, melt butter in a large frying pan. Sauté garlic and spinach until soft. Add anchovies, pepper and walnut oil. Stir well. Add the Faisselle; stir until mixture becomes saucy. Add drained pasta to mixture. Garnish with chopped walnuts. Makes 4-6 servings.