In a mixer bowl, combine bread flour, sugar, salt, dry yeast, milk and plain yogurt, leaving the unsalted butter for later use.
Using a dough hook, knead the dough on low speed to gently mix the ingredients for 15-30 seconds.
Gradually raise the speed. Knead for 5 minutes.
When the dough begins to form a ball, do a windowpane test (see Note 1).
Add in unsalted butter. then continue kneading for 10 minutes. Do a windowpane test again (see Note 2).
Take out the dough from the mixer bowl and shape it into a ball.
Place it back into the mixer bowl, cover it with a damp cloth or cling film and proof it for 1hr (or until double in size) in room temperature.
After 1 hour, take out the dough and check if it has properly proofed (see Note 3).
Sprinkle some flour on the dough surface and pat the dough to release air bubbles.
Divide the dough in half and work on one piece at a time.
Gently flatten the dough and shape it into a rectangular shape.
Fold top and bottom sides into the centre. Rotate the dough, gently flatten it, and fold the other two sides.
Cover them with a damp cloth or cling film. Let them rest for 15 minutes.
Sprinkle some flour on the dough surface, roll the dough into a rectangular shape.
On the longer side, fold each side into the centre. Roll the dough to flatten it.
Starting from the short side, roll up the rectangular dough into a cylinder shape.
Pinch to seal the seams and the ends.
Repeat for the other piece.
Place the loaves into a loaf tin and proof for the 2nd time (about 45 minutes to 1 hour) at room temperature.
Preheat the oven to 180°C.
Gently brush the loaves with egg wash.
Bake for 30-35 minutes.