Preheat oven to 425 degrees.
Combine the white and brown sugar, salt, cinnamon, ground ginger, nutmeg, allspice and cloves in a bowl. In a separate bowl, beat the eggs lightly. Add the pumpkin to the eggs, alternating with the sugar and spice mixture. Gradually add the evaporated milk and vanilla extract.
Pour into the prepared pie shells. Do not overfill the pies (there may be some filling left over). Bake at 425 degrees for 15 minutes, then turn the oven down to 350 and continue to bake for an additional 40-50 minutes. Pie is done when knife inserted in center comes out clean. Sprinkle with ginger nibs and cool on wire racks.
Serve with whipped cream.
You can substitute the individual spices in this recipe for an equal amount of The Spice House's Pumpkin Pie Spice. Pie crusts can be purchased pre-made, otherwise we find that the Joy of Cooking cookbook's recipe for standard pie crust is fantastic.