Set oven rack in middle position. Preheat oven to 375. Put prepared sweet potatoes (see below) in bowl of stand mixer fitted with paddle attachment. With mixer running on low, add butter. Add brown sugar and sugar. Add eggs, one at a time. Add heavy cream and vanilla. Don’t overbeat. Add cinnamon, clove, ginger and salt
Pour batter into pie shells. Bake for about an hour or til tester inserted into pie comes our clean. The center of pie should wiggle a bit. Cool 2 to 3 hours on rack. Serve with whipped cream. Store covered with a paper towel and plastic wrap in refrigerator.
How to prepare sweet potatoes: Prick them with a fork and put them on foiled covered (Shiny side up) metal baking pan that has been coated with vegetable spray. Bake at 400 for 1 hour. Put baking pan on cooling rack. Carefully cut hot sweet potatoes in half lengthwise so that they will cool faster. When potatoes are cool enough to handle, scoop out insides. Throw away the skins. Put them in the bowl of food processor fitted with metal blade. Weigh sweet potato pulp after scooping it, since size and weight are hard to discern with your eyes alone. Process til potatoes are soft and fluffy. For two pies, you will need 2 1/2 lbs. or 40 oz. raw sweet potatoes to make 22 oz. of processed cooked sweet potato, about 4 large potatoes to start. Don’t use canned sweet potatoes because freshly baked potatoes still retain some of their fiber.