Chinese Steamed Custard Buns

Instructions

1. Prepare the dough
   In a large mixing bowl, combine flour, sugar, salt, and instant yeast. Gradually add warm water and mix until a dough forms. Add vegetable oil and knead for 8-10 minutes until smooth and elastic. Cover with a damp cloth and let rise in a warm place for 30 minutes or until doubled in size.
2. Make the custard filling
   In a medium bowl, whisk together egg yolks, softened butter, and powdered sugar until smooth. Add evaporated milk, custard powder, cornstarch, and vanilla extract. Mix until well combined. Cook the mixture over low heat in a small saucepan, stirring constantly until it thickens to a spreadable paste (about 5-7 minutes). Transfer to a bowl, cover with plastic wrap directly touching the surface, and refrigerate for 20 minutes.
3. Divide and shape the dough
   Punch down the risen dough and sprinkle with baking powder. Knead for another 2-3 minutes to incorporate the baking powder. Divide the dough into 12 equal pieces (about 40-45g each). Shape each piece into a ball and cover with a damp cloth to prevent drying.
4. Fill the buns
   Take one dough ball and flatten it into a 4-inch circle, keeping the center thicker than the edges. Place about 1 tablespoon of chilled custard filling in the center. Gather the edges upward and pinch to seal completely. Place the bun seam-side down on a small square of parchment paper. Repeat with remaining dough and filling.
5. Rest before steaming
   Arrange the filled buns in a steamer basket, leaving at least 1 inch of space between each bun as they will expand during steaming. Cover with the steamer lid and let rest for 15 minutes.
6. Steam the buns
   Bring water to a boil in a wok or pot. Place the steamer basket over the boiling water and steam the buns for 10-12 minutes on medium-high heat. Turn off the heat but do not open the lid. Let the buns rest in the steamer for 2 more minutes to prevent them from collapsing.