Preheat oven to 350 degrees. Grease 2 (or 4) 1-cup oven safe custard cups or gratin dishes with the butter.
In a blender, combine the sweet potatoes, milk, eggs, sugar, spices and vanilla. Blend until smooth.
Pour blended mixture evenly between prepared custard cups, about 3/4 cup per dish. Sprinkle the top of each custard with about a teaspoon of chopped pecans. Place custards on a baking sheet and bake for 25 to 30 minutes or until browned, set in the center and slightly puffed.
Serve warm or chilled.
Notes
Adapted from Healthy Cooking for Two (or Just You)