Heat oven to 350 degrees F.
Beat ricotta, sugar, flour, eggs, rind, vanilla until smooth. Stir in chocolate; scrape into pie shell.
Bake in 350 degree F oven 40 minutes or until knife inserted in center comes out clean. Cool on rack. Chill. Serve cold. Garnish with whipped cream and chopped pistachios if you wish. Makes 8 servings.
