Combine bread flour, cake flour, sugar, dry yeast, salt, water, and milk in a bowl.

Mix until the ingredients form a ball.

Knead the dough until smooth.

Incorporate butter and continue to knead until the dough is elastic.

Check for gluten development by observing if you can see your fingers through the stretched dough.

Place the dough in a lightly greased bowl.

Allow the dough to rise in a warm place (40C if possible) for 50-60 minutes, or until doubled in size.

Deflate the dough and divide it into 8 equal pieces.

Let the dough rest for 10 minutes, covered with a damp towel.

Shape each piece into a smooth ball by pulling the outside edges towards the center.

Optionally, dust the outside of the balls with strong flour.

Allow the shaped dough balls to rise a second time, until expanded.

Preheat oven to 190C.

Reduce temperature to 180C and bake for 15 minutes, or until golden brown.

Let cool slightly before serving.