Pineapple Bun Bo Lo Bao

In a large bowl, combine flour, sugar, yeast, and salt for the bun dough. Add warm milk and the egg, then mix until a shaggy dough forms. Knead for 5-7 minutes until smooth. Add the softened butter and continue kneading for another 5-10 minutes until the dough is elastic and passes the windowpane test. Place the dough in a lightly oiled bowl, cover, and let it proof in a warm place for 60-90 minutes, or until doubled in size.

While the dough is proofing, prepare the topping. In a separate bowl, combine flour, powdered sugar, and milk powder (if using). Add the cold, cubed butter and cut it into the dry ingredients using a pastry blender or your fingertips until the mixture resembles coarse crumbs. Add the egg yolk and mix until a soft dough forms. Do not overmix. Wrap the topping dough in plastic wrap and chill in the refrigerator for at least 30 minutes.

Once the bun dough has doubled, gently punch it down to release air. Transfer it to a lightly floured surface and divide it into 8 equal portions. Roll each portion into a smooth ball. Place the dough balls on a baking sheet lined with parchment paper, leaving space between them.

Remove the chilled topping dough from the refrigerator. Divide it into 8 equal portions. Flatten each portion into a thin disc, about 3-4 inches in diameter. Carefully place one topping disc over each dough ball, gently pressing down to adhere it. Use the back of a knife or a dough scraper to create a criss-cross pattern on the topping, mimicking a pineapple's skin. Brush the topping lightly with egg wash.

Cover the shaped buns loosely with plastic wrap and let them proof in a warm place for another 30-45 minutes, or until visibly puffy. Towards the end of the second proofing, preheat your oven to 180C (350F).

Bake the pineapple buns in the preheated oven for 18-20 minutes, or until the topping is golden brown and the buns are cooked through. If the topping browns too quickly, you can loosely tent the buns with aluminum foil. Once baked, remove from the oven and transfer to a wire rack to cool slightly before serving. Enjoy warm!