Sweet Custard-Filled Steamed Buns (Nai Wong Bao)

In a large bowl, combine 2 cups all-purpose flour, 1 tablespoon active dry yeast, and 1/4 cup granulated sugar. Gradually add 1/2 cup warm water and 2 tablespoons vegetable oil, mixing until a shaggy dough forms. Knead on a lightly floured surface for 8-10 minutes until smooth and elastic. Place the dough in a lightly oiled bowl, cover, and let rise in a warm place for 45 minutes, or until doubled in size.

While the dough rises, prepare the custard filling. In a medium saucepan, whisk together 1/2 cup custard powder and 1/4 cup granulated sugar. Gradually whisk in 1/2 cup milk until smooth. Cook over medium-low heat, stirring constantly, for 5-7 minutes until the mixture thickens to a pudding-like consistency.

Remove the custard from heat and stir in 2 tablespoons melted unsalted butter until fully incorporated. Transfer the custard to a bowl, cover with plastic wrap directly on the surface to prevent a skin from forming, and chill in the refrigerator for at least 20 minutes until firm enough to handle.

Once the dough has risen, punch it down gently and divide it into 8 equal pieces. Roll each piece into a smooth ball, then flatten it into a 4-inch (10 cm) circle.

Take a spoonful of the chilled custard filling and place it in the center of each dough circle. Gather the edges of the dough around the filling, pinching them together tightly to seal the bun. Place the sealed buns seam-side down on individual squares of parchment paper.

Arrange the buns in a steamer basket, ensuring there is space between them for expansion. Cover the steamer and let the buns rest for another 15 minutes.

Steam the buns over rapidly boiling water for 10-12 minutes on high heat, or until they are puffed and cooked through. Do not overcrowd the steamer; steam in batches if necessary.

Carefully remove the steamed buns from the steamer and serve warm.