Grease an 8x8-inch baking dish with oil or butter.

In a pot, combine 2 cups of coconut milk and 1 cup of water, then add washed glutinous rice and cook over medium heat for 15-20 minutes.

In another pot, combine 1 cup of Ube, 1 cup of coconut milk, and 1 cup of evaporated milk. Cook for 10-15 minutes until Ube is fork-tender, then mash and mix in 1 cup of condensed milk.

Fold the Ube mixture into the sticky rice and spread it evenly in the baking dish.

Whisk together 1 cup of condensed milk, 1 cup of evaporated milk, and 4 egg yolks, then mix in 2 tablespoons of flour until smooth.

Pour the custard over the Ube rice layer and bake at 180°C (350°F) for 15-25 minutes until the custard is set.

Allow to cool before slicing and serving.