Wash purple yams carefully, scrub skin until no dirt is left on the skins, then boil whole purple yams in salted water for about 30–40 minutes or until fully cooked and softened, then strain, cool, peel skins.

Blend purple yam with evaporated milk, condensed milk, and coconut milk on high speed until very smooth, then transfer to saucepan, add sugar and reduce over medium-low heat for about 45 minutes, stirring as needed, to jam texture.

Add butter, ube extract, vanilla extract, purple color, salt, stir to combine, remove from heat, taste and adjust as needed.