Prepare the dough: In a mixing bowl, combine high gluten flour, sugar, powdered milk, yeast, liquid milk, and egg. Knead until a homogeneous dough forms. Gradually add unsalted butter, continuing to knead until the dough is smooth and elastic. Cover and let it rest in a warm area until it doubles in size (about 1 hour).

Shape it: Once risen, gently deflate the dough and divide it into 6 equal portions. Shape each portion into a ball and let rest for an additional 15 minutes.

Prepare the puff pastry: In another bowl, mix together the unsalted butter, sugar, egg liquid, low gluten flour, and powdered milk. Divide this mixture into 6 equal portions and flatten each into a thin circle.

Assemble the buns: Roll each dough ball into a disc, and place a puff pastry circle on top of it. Use a scraper to create decorative lines on the topping. Cover and let proof until they increase to 1.5 times their original size (about 30 minutes).

Bake: Preheat your oven to 180°C (356°F). Brush the buns with egg yolk for a golden finish and bake for 25 minutes or until they achieve a beautiful golden-brown color.