Pour enough cooking oil into a deep pot to fully submerge the mantou. Heat the oil on high until it reaches about 50% of its maximum temperature. To test, insert a chopstick into the oil. If small bubbles rapidly form around it, the oil is ready.

Place the prepared mantou into the oil and fry over medium-low heat. Use chopsticks to turn the mantou frequently for even cooking. Fry until both sides are golden brown (about 3–5 minutes, depending on mantou size and heat intensity).

Once golden brown, remove the mantou with a slotted spoon. Drain excess oil and place them on a plate.

In a heavy-bottomed flat pan, combine 300ml milk and 50g sugar. Stir until the sugar is fully dissolved.

Heat the mixture over medium heat, stirring constantly to prevent sticking and burning. The milk will thicken and slightly darken as it heats.

When the milk is thick enough to coat the back of a spoon and stirring feels resistant, reduce the heat to low. Simmer for an additional 2–3 minutes while continuing to stir.

Transfer the condensed milk to a small bowl or cup and let it cool slightly before serving.