Soft, buttery Japanese salt bread (shio pan) with a golden crust and a cold butter center that melts as you tear it open. These rolls are easier to make than they look and taste like they came straight from a Japanese bakery.
Make the dough: In a large mixing bowl, combine bread flour, cake flour, and remaining 30g sugar. Pour in the milk-yeast mixture and stir until a shaggy dough forms.
Knead: Add salt and softened salted butter. Knead until smooth and elastic - 15-20 minutes by hand or 10 minutes in a stand mixer with dough hook. The dough should be soft, slightly tacky, and pass the windowpane test.
5 grams (1 teaspoon) salt, 29 grams salted butter
First rise: Cover the bowl with plastic wrap or a damp towel and let rise in a warm place for 1 hour or until doubled in size. Don't overproof - it should exactly double, not triple.
Divide and rest: Punch down the dough to degas. Divide into 12 equal pieces (about 57g each). Form each piece into a smooth ball. Cover and let rest for 10-15 minutes.
84 grams salted butter
Shape the rolls: Working with the first ball you formed (while others rest), roll it into a long rectangle or oval about 4-5 inches long. Place one piece of cold butter (7g) at one end. Roll tightly toward the other end, like a mini jelly roll. Pinch the seam firmly to seal. Repeat with remaining dough balls in the order you formed them.
Second rise: Place shaped rolls seam-side down on a parchment-lined baking sheet, spacing them 2 inches apart. Cover loosely and let rise for 30 minutes until noticeably puffy.
Prep for baking: Preheat oven to 375°F. Brush/ Spray rolls with water or milk and sprinkle with Maldon sea salt flakes.
Maldon sea salt flakes
Bake: Bake for 12-15 minutes until deep golden brown on top. The rolls should sound hollow when tapped on the bottom.
Cool and serve: Let cool for 5 minutes on the baking sheet, then transfer to a wire rack. Serve warm - tear one open and watch that butter pool out.
Notes
• Butter temperature matters - The filling butter must stay cold so it doesn't melt into the dough before baking. Cut it ahead and keep it in the fridge until you're ready to roll.• Cake flour creates tenderness - The mix of bread flour and cake flour gives you structure with a softer, more delicate crumb than all bread flour.• Don't overproof - Watch the first rise carefully. Overproofed dough loses structure and your rolls won't rise properly in the oven.• Roll order matters - Shape rolls in the order you formed the balls. The first balls have rested longest and are easiest to roll without springing back.• Seal tightly - Really pinch that seam. If it's loose, butter will leak out during baking and you'll lose that molten center.• Make ahead - After shaping, cover and refrigerate overnight for the second rise. Bring to room temperature for 20-30 minutes before brushing and baking.• Storage - Keep in an airtight container at room temperature for up to 2 days. Reheat in a 300°F oven for 5 minutes to bring back that fresh-baked texture.• Freezing - Freeze baked rolls for up to 1 month. Thaw at room temperature and reheat in the oven before serving.