We like the frozen ube by Tastee because the desired halaya consistency is easy to render. The halaya should hold together well and come away from the sides of the pot as you stir it. It's easy to find in your local Filipino or Asian grocery store.
Frozen, grated ube, one packet, defrosted
1 stick of butter, cut roughly into cubes to help melting (salted or unsalted)
1/3 cup of granulated sugar
1 can of condensed milk
1/4 cup of fresh milk (evaporated or whole milk)
Pinch of salt. Dat's it.
As true to its name, dump all ingredients into a pot and stir, stir, stir until well combined. Again the consistency you want to achieve is like a thick oatmeal that sticks to a spoon when turned upside down. Challenge yourself not to eat this purple goodness straight out of the pot. Difficulty high.
But hey, if you want to find fresh ube or purple yam and cook and mash that yourself, go all out, man. And send us pictures!