In a mixing bowl, combine the sifted bread flour, cake flour, milk powder, sugar, and instant yeast. Pour in the cold water and start mixing on low speed until the dry ingredients are fully moistened.
Add the unsalted butter and salt, then continue mixing until the dough comes together and is no longer sticky.
Continue mixing until the dough becomes smooth and elastic and can be stretched thin without tearing (windowpane stage).
Transfer the dough to a lightly greased bowl, cover with cling wrap, and let it ferment for 30 minutes or until doubled in size. Gently punch out the air, then divide the dough into 10 equal portions. Cover and let the dough rest for 10 minutes.
Take one portion of dough and roll it into a teardrop shape. Repeat with the remaining dough and keep them covered to prevent drying.
Roll each piece into a long strip, about 5 × 15 cm (adjustable depending on dough elasticity). Place a cold butter block on the wider end of the dough.
Roll the dough tightly from the wide end toward the tip to form a croissant-like shape. Place the shaped dough on a baking tray and cover loosely with cling wrap. Let it proof for 30–45 minutes, or until puffy and nearly doubled in size.
Lightly spray the dough with water and sprinkle flaky salt on top. Bake in a preheated 220°C (430°F) oven for 12–15 minutes, or until golden brown.
Remove from the oven and immediately brush with melted butter for a glossy finish. Enjoy your freshly baked salt bread while warm.
Notes
Keep the butter cold Refrigerate the butter blocks until right before shaping. Cold butter melts slowly in the oven, creating the signature hollow crumb and rich buttery center.
Add steam during baking Toss a few ice cubes onto a hot tray or the bottom of the oven right after loading the bread. The steam helps keep the surface moist early on, allowing better oven spring and a lighter texture.
Don’t overproof the dough - The shaped dough should look puffy but still slightly firm. Overproofing can cause the butter to leak out too quickly during baking.
Seal the dough snugly around the butter - Roll the dough firmly so the butter is well enclosed. Loose rolling can lead to butter leakage and uneven layers.
Use flaky salt, not fine salt - Flaky salt gives a pleasant crunch and balanced salinity without making the bread taste overly salty.
Enjoy while warm - Salt bread is at its best fresh from the oven, when the crust is lightly crisp and the inside is soft and buttery.