In a small bowl, mix together ube powder and granulated sugar. This is your sweetened ube powder.
Add cream, milk, toasted coconut syrup, and 1 ½ tablespoon sweetened ube powder to a mason jar (or other airtight container) and shake vigorously. Or mix all ingredients in a bowl until well combined. This is your ube coconut cold cream... Keep it in the fridge until you're ready to turn it into cold foam right before using.
To turn into foam, you can either use an electric frother, hand mixer, or blender with ⅓ cup mixture at a time. Alternatively, you can shake the mixture vigorously in a mason jar until it's frothy.