PURPLE YAM JAM

Ingredients
1       kilo ube yam root
1/2    cup butter or margarine
1      can (14 ounces ) evaporated milk
1/2   teaspoon of vanilla (optional)
 2      cans (12 ounces) condensed milk

Cooking procedure: 
Estimated preparation and cooking time: 2 hours
Boil the unpeeled ube yam in water and simmer for 30 minutes on a pot. Drain and let cool.
Peel and thinly grate the ube yam.
Heat a big wok in medium heat.
Melt butter or margarine, add the condensed milk and vanilla flavoring. Mix well.
Add the 1 kilo grated ube yam. Adjust the heat to low
Keep on mixing the ingredients for about 30 minutes or until sticky and a bit dry (but still moist). Add the evaporated milk and continue to mix for another 15 minutes.
Let cool and place on a large platter.
Refrigerate before serving the halayang ube.