Boil together buko juice, sugar and pandan leaves until sugar dissolves completely and mixture thickens.
Add vanilla extract. Remove pandan leaves. Cook grated coconut in a pan with a little oil until it turns slightly brown.
Add syrup and thicken with a little flour or cornstarch diluted in water. Keep stirring so that syrup coats the grated coconut completely, the mixture thickens and bukayo gets cooked completely.
When cooked, transfer bukayo to a bowl. Form into small balls while hot.
Use plastic wrap or wax paper to insulate your hands from the hot mixture.