In a medium mixing bowl, whisk well to combine milk, eggs (remove 1 egg white from the eggs, about 2 tablespoons and set aside), yeast and sugar until fully dissolved, about 2 minutes. Whisk in 1 cup flour and mix well until smooth.

In a large mixing bowl, add remaining 3 cups flour, diced butter and salt. Mix evenly with a spatula. Pour in the egg flour mixture and stir well to combine until it forms a shaggy dough, scraping down the sides of the bowl (there should be no dry flour particles visible). Cover the bowl with cling wrap and let dough rise at room temperature (preferably in a warmer area) for 1 hour until doubled.

Knead the dough on a clean lightly floured surface for 8-10 minutes until it changes from a sticky shaggy dough into a smooth and soft dough ball. Apply a little bit of flour on your hands if needed and slap and fold the dough to further build gluten and distribute butter evenly in dough. A well-kneaded dough is smooth and can hold its shape. Also, when you give the dough ball a firm poke with your finger, the indentation should bounce right back. If it doesn’t bounce back and stays like a dimple, keep kneading for a few minutes.

Flatten the dough, divide it into 9 equal pieces with a bench scraper, and shape them into smooth balls by cupping the dough in your palm and making circular motions.It should take less than 30 seconds to roll each piece into a smooth ball.

Arrange dough balls in a lightly oiled 1.5 lb. loaf pan (10x5-inch loaf pan). Cover with cling wrap and let it rise until almost doubled in size, about 45 minutes depending on the room temperature. The dough will rise up to the rim of the loaf pan. You can also braid the brioche as in challah bread and bake it in the loaf pan or in a sheet pan.

Preheat oven to 375 F.

Brush the reserved egg white evenly over the top and sprinkle with salt flake. The egg white creates shine and makes the salt stick to the top.

Bake for 30-35 minutes until the crust turns golden brown. Transfer the loaf onto a wire cooling rack to cool completely before slicing, about 30 minutes.