Mix pumpkin with whipping cream. Add eggs,one at a time, mix after each addition. In another bowl, mix sugar, cinnamon, ginger, nutmeg, cloves and salt. Add to pumpkin mixture. Mix well. Pour into pie shell. Bake in preheated 425-degree oven for 10 minutes. Reduce temperature to 350 degrees and bake for 45 minutes or until knife inserted near center comes out clean. Cool completely. Spread whipped topping on top of pie and sprinkle with walnuts. Refrigerate leftovers.