Boil the water: Bring a generous amount of water to a rolling boil in a pot. The water should be at a full, vigorous boil before you add the sago.

Cook the sago: Add the dried sago to the boiling water. Do not wash the sago first—add it directly from its package. Reduce the heat to medium-low, cover the pot with a lid, and cook for 15 minutes. Stir frequently during cooking to prevent the sago pearls from sticking to the bottom of the pot or to each other.

Steam the sago: After 15 minutes, the sago pearls should have only a tiny white dot left visible in their centers. Immediately turn off the heat. Cover the pot tightly with the lid and let the sago steam in the residual heat for 15 minutes. This steaming step is essential—it allows the sago to become completely transparent with no white dots without overcooking.

Rinse and drain: Once the sago is fully transparent, remove it from the pot and rinse it under cold boiled water or ice water. This stops the cooking process and removes excess starch, resulting in bouncy, separate pearls that don't stick together. Drain well and set aside.

Make the dough: In a mixing bowl, combine 100 g of glutinous rice flour with 80 g of pure milk. Knead the mixture until it forms a smooth, pliable dough that does not crack when you press it. If the dough is too dry, add a few drops more milk; if too wet, add a tiny bit more flour.

Shape the balls: Pinch off small pieces of dough and roll them between your palms to form tiny, bite-sized balls. Keep them uniform in size so they cook evenly.

Cook the rice balls: Bring a separate pot of water to a boil. Carefully drop the glutinous rice balls into the boiling water. Cook until they all float to the surface—this indicates they are nearly done. Once floating, continue cooking for 1 more minute.

Rinse and cool: Remove the cooked rice balls from the water and rinse them immediately under cold water. This step is essential—it stops the cooking process, removes excess starch, and gives the rice balls a wonderfully chewy, bouncy texture. If you skip this rinse, they will become soft, sticky, and prone to clumping together.

Prepare the mango: Take one ripe mango. Cut it in half around the pit. Reserve one half to be cut into small, bite-sized mango cubes. Take the other half and mash or puree it thoroughly until it becomes a smooth, thick mango paste. You can use a fork, a potato masher, or a blender for this step.

Assemble the cups: Layer the ingredients in each cup in the following order, starting from the bottom:

First, spoon in a generous layer of mango paste.

Next, add a scattering of fresh mango cubes.

Then, add a portion of cooked glutinous rice balls.

Follow with a portion of cooked, drained sago pearls.

Finally, pour in enough pure milk to fill the cup to your desired level.

Serve immediately or chill: The dessert can be enjoyed right away, or you can refrigerate it for 30 minutes to serve it extra cold. Stir gently before drinking to combine all the layers.