If you can find it, you could use ube jam or powdered ube instead of fresh cooked ube.
Loved this shake and the purple colour is a bonus! The kids loved it, too. - 06 Feb 2018
This is a yummy way to use ube! The shake reminds me of an ube smoothie I tried at my local boba shop. My toddler son also loved it. Thanks for the recipe! - 18 Jul 2018 (Review from Allrecipes US | Canada)