Combine coconut milk and water in a bowl and mix well.

Remove 1/3 of the mixture and place in a separate bowl.

Add cornstarch to the smaller bowl with the coconut milk mixture and whisk until smooth.

Pour the remaining 2/3 of the coconut milk and water mixture into a saucepan.

Add sugar to the saucepan.

Bring the mixture in the saucepan to a boil over medium heat.

Reduce the heat to low.

Pour in the cornstarch and coconut milk mixture from Step 3.

Stir constantly with a wooden spatula to prevent burning and sticking.

Make sure to incorporate the batter that sticks to the sides of the pan to avoid lumps.

Continue stirring for 10-15 minutes, or until the mixture thickens significantly.

The mixture is ready when you can see the bottom of the pan as you stir.

The color should be a shiny, nice, white color.

While still hot, pour the mixture into a baking tin (approximately 8x8 inches).

Even out the surface with a spatula or spoon.

Let the hau pia set at room temperature or in the refrigerator.

Hau pia is usually 1.5-2 cm thick.

Once set, cut into squares.

Serve chilled.