Place the sweet potato in a saucepan with just enough water to cover. Bring to a boil, and cook until fork tender, about 5 minutes. Drain and mash with a fork or potato masher.
Preheat the oven to 425 degrees F (220 degrees C). Divide the pie crust into 24 small balls. Press them into the cups of two 12 cup mini muffin pans to make tartlet shells. Set aside.
Spoon the sweet potato into a blender or food processor, and add the evaporated milk, egg whites, white sugar, brown sugar, cinnamon, nutmeg, and cloves. Puree until smooth. Spoon about 1 tablespoon of this mixture into each tart shell.
Bake for 10 minutes in the preheated oven, or until a toothpick inserted into one of the tarts comes out clean. Cool in the pans over a wire rack. Garnish each tart with a cranberry half before serving.
