Preheat oven to 375°F. Scrub sweet potato. Prick sweet potato all over with a fork. Place on a baking sheet and bake until tender, about 1 hour. Cool until easy to handle (about 30 minutes).
Peel sweet potato and puree in a food mill, baby food grinder, or small food processor. Use within 1 day, or freeze up to 1 month.
Spoon finished food into ice cube trays. Cover with waxed paper and freeze until firm. When ice cubes are frozen, remove cubes from tray and store in a resealable plastic freezer bag or freezer container. Label package with contents and date. Use within 1 month. Before serving, let thaw in the refrigerator overnight.
Heat thawed mixture to lukewarm in a small dish set in a pan of hot water. Stir before serving. Always sample a small bite to make sure the food is not too hot.