In a large bowl, combine bread flour, cake flour, sugar, salt, and dry yeast.

Add warm water and warm milk to the dry ingredients and mix with a spatula until a shaggy dough forms.

Turn the dough out onto a work surface and knead for 7-8 minutes.

Flatten the dough, add the butter, and knead for another 14-15 minutes until the dough is smooth and elastic.

Check if the dough passes the windowpane test, then form it into a smooth ball.

Place the dough in a bowl, cover with plastic wrap, and let it ferment in a warm place until it doubles in size (about 80 minutes).

Gently press the fermented dough to release the gas.

Divide the dough into 6 equal pieces, about 53-54g each.

Shape each piece of dough into a teardrop shape.

Cover the dough pieces and let them rest for 15 minutes (bench time).

Roll out a piece of rested dough into a long triangle, about 10cm wide and 30cm long.

Place a 7g piece of butter at the wide end of the dough.

Roll the dough tightly from the wide end down to the tip, sealing the butter inside.

Arrange the shaped rolls on a baking sheet, cover, and let them proof for a second time until 1.5 times their size (about 40 minutes).

After proofing, mist the rolls with water and sprinkle rock salt on top.

Bake in an oven preheated to 200°C (392°F) for 13-15 minutes.

After baking, brush the rolls with the melted butter from the pan and let them cool on a wire rack.