Warm the milk: Heat the milk until warm to the touch (about 105–110°F / 40–43°C). Stir in the sugar until dissolved. Sprinkle yeast on top and let stand 5–10 minutes until foamy.

Mix dry ingredients: In a large bowl, whisk flour and salt. If using instant yeast, combine it here instead of blooming.

Combine wet and dry: Add the foamy milk, melted butter, and egg to the flour. Stir with a wooden spoon until a shaggy dough forms.

Knead the dough: Turn onto a lightly floured surface and knead for 8–10 minutes until smooth and elastic.

First rise: Place dough in a lightly oiled bowl, cover with a damp towel, and leave in a warm spot until doubled — about 60–75 minutes.

Fold in chocolate: Gently deflate the dough and spread it into a rectangle. Scatter the chocolate chips over the surface and fold the dough a few times.

Shape the buns: Divide dough into 12 equal pieces. Tuck edges under and roll each piece into a smooth ball. Place on a baking tray lined with parchment.

Second rise: Cover loosely and let rise another 30–45 minutes until puffy. Preheat oven to 375°F (190°C) during the last 10 minutes.

Egg wash: Brush buns gently with the egg yolk and milk wash for a golden sheen.

Bake: Bake for 12–16 minutes until golden brown and the bottoms sound hollow when tapped.

Cool and enjoy: Transfer to a rack and cool slightly.