01 - Combine flour, sugar, salt, and yeast in a large bowl, keeping yeast separate from salt. Pour in lukewarm milk, melted butter, and cracked egg. Mix thoroughly until sticky dough forms.
02 - Knead dough 7–10 minutes until smooth and elastic. Transfer to greased bowl, cover, and let rise 1 hour until doubled in volume.
03 - Punch down risen dough, shape into rectangle, cover, and refrigerate 30 minutes to firm.
04 - On floured surface, roll dough to 12 x 16-inch rectangle. Arrange cold butter slices over two-thirds of dough surface.
05 - Fold unbuttered third over butter section, then fold remaining third on top to form neat rectangle. Rotate 90° so openings face you.
06 - Roll dough again to 12 x 16-inch rectangle. Fold into thirds, wrap, and refrigerate 30 minutes.
07 - Repeat rolling, folding, and refrigerating process twice more for total of three turns, chilling 30 minutes between each.
08 - After final chill, roll dough to approximately 8 x 16 inches. Roll tightly from short edge into loaf form.
09 - Place seam-side down in greased 9 x 5-inch loaf pan. Cover loosely and let rise until doubled, about 1 hour.
10 - Preheat oven to 375°F. Whisk egg with milk for wash and brush evenly over loaf surface.
11 - Bake 35–40 minutes until deep golden brown and loaf sounds hollow when tapped. Cover with foil if browning too rapidly.
12 - Let cool in pan 10 minutes, then transfer to wire rack. Cool completely before slicing for clean cuts.