Press the butter to soften a little; set aside. Warm the water-milk mixture with a microwave until reaches 35-40℃ / 95-104 °F. (If the room temperature is high, around 20°C / 68°F.)

Put bread flour, whole wheat flour, cane sugar, and instant dry yeast in a large bowl. Pour 80％ of the water-milk mixture into the bowl like drawing circles. Mix roughly.

Pour the remaining water mixture against powdery places. Mix roughly until it becomes a single mass. Put onto a work surface.

Knead for a min, flatten it and put salt on. Knead it for 2-3 mins while stretching and pressing until combined.

Hit the dough against the work surface and fold, repeat 30 times. Roll it alternate left and right (1 set), repeat 30 sets. Repeat 30-hitting and 30-rolling alternately for 7-8 mins.

Flatten and spread it, put unsalted butter on. Knead well with your hands until combined for around 2-3 mins while pressing and stretching.

Repeat hitting and rolling for 7-8 mins in the same way as before. Please make the dough smooth and elastic. Make it the ball shape.

Place it in a lightly oiled bowl. Cover the bowl with plastic wrap. Let it rise in a warm place (about 35℃ / 95°F) until doubled in size, 40-50 mins.

Finger Dent Test! Press your floured finger into the dough. If the dent springs back a little, and it stays without filling in, it’s ready.

Punch the air out. Divide it into 2 equal pieces.

Using your hand to flatten one piece into a rough rectangle. Start to roll from one of the shorter ends and roll it up into a cylinder. Rotate it 90 degrees and roll it up with the seam side facing up. Repeat with another piece.

Cover with a damp towel and let it rest for 10-15 mins. (After 10-15 mins, it's will rise a little.)

Punch the air out. Use a rolling pin to roll out one piece into about 15 x 25 cm (5.9 × 9.8 inches) oval or rectangular.

Fold it towards the center from left and right to overlap about 1 cm (0.4-inch). Start to roll from one of the shorter ends and roll it up. Pinch the edges to seal well. Repeat with another piece.

Place each dough at both ends of a lightly oiled pan with the seam side facing down. Let it rise in a warm place (about 40℃ / 104°F) until the top of the dough reach the height of the loaf pan, about 30-40 mins. Preheat the oven to 220℃ / 428°F.

I used my oven to rise the dough until the top of the dough reach the height of the loaf pan. The dough needs to rise a little more, but the oven cannot be used for rising because the oven needs preheating. So I put the pan on the container with warm water to rise until the top of the dough is higher 1 cm (0.4'') than the height of the pan.
Lightly cover with plastic wrap to prevent drying.

Spray water lightly (about 3 times). Bake it at 200℃ / 392 °F for 30 mins until golden brown.

Drop the pan to prevent shrinkage. Remove the bread from the pan and cool it down on a rack. Done!