Whisk the warm milk, yeast, and sugar together in a mixing bowl. Allow mixture to sit for about 5 minutes or until foamy on top.

Add the salt, butter, and 2 cups (250g) of flour. Beat on medium speed for 2 minutes, stopping to scrape down the bowl as needed.

Add the remaining flour and beat on low speed until a soft dough forms and pulls away from the sides of the bowl.

Knead the dough for an additional 5 minutes in the mixer or by hand on a lightly floured surface.

Lightly grease a large bowl with oil or nonstick spray. Place the dough in the bowl, cover, and allow to rise for 1.5–2 hours or until nearly double in size.

Punch down the dough to release the air. Flatten the dough into a 10×14-inch (25x35cm) rectangle and chill in the refrigerator for 20 minutes.

Cut the salted butter into 1/4-inch thick slices.

Remove the dough from the refrigerator, and line butter down the center of the dough. Fold the edges over the butter. Roll out to a 9×12-inch (23x30cm) rectangle and refrigerate for 20 minutes.

Repeat the lamination process (rolling and folding) two more times, refrigerating for 20 minutes in between.

Roll the dough into a 9×12-inch rectangle for the final time. Roll it up from one end like a jelly roll and cut into 5 even rolls.

Grease a 9×5-inch loaf pan and place rolls seam side down in the pan. Cover and let rise for 45–60 minutes until slightly puffy.

Preheat the oven to 350°F (177°C). Whisk egg wash ingredients together and brush over the risen rolls.

Bake the loaf for 1 hour until golden brown, tenting with aluminum foil after 25 minutes if necessary. Check doneness with an instant-read thermometer reading 195°F (90°C).

Let cool for 30 minutes in the pan before transferring to a wire rack to cool for an additional 15 minutes before slicing.