In a medium heavy bottom sauce pot, whisk together ube powder, sugar, evaporated milk, sweetened condensed milk, and water until smooth.
Set over low-medium heat. Stir frequently to ensure mixture does not burn along the sides. Cook for 15-20 minutes until mixture has thickened to a paste-like consistency.
Remove from heat. Stir in butter, vanilla, and ube extract. Transfer to a heat safe container. Allow to cool. Cover and let chill in the fridge for at least 4 hours, or overnight.