In the bowl of a stand mixer, combine the flour, sugar, salt and yeast.
Add in the warm water and mix for 1 minute.
Add the melted butter to the milk and pour into the mixer. Mix the dough with the dough hook, scraping down the sides as needed until a soft ball of dough is formed.
If the dough is still sticking to the sides of the bowl, add in additional flour 1 tablespoon at a time until it pulls away from the sides. Knead on low speed for 3-5 minutes until all of the ingredients are incorporated.
Turn up the speed to medium low and continue to knead for 7-8 minutes.
Roll the dough out onto a lightly floured surface and roll out into a rectangle, about 24 x 12 inches and 1/2 inch thick. Place on a baking sheet and cover with plastic wrap, place in the refrigerator for at least to hours, up to 8.
While the dough is in the refrigerator, take the 1 1/2 cups of butter and place between 2 pieces of parchment paper. Beat with a rolling pin and roll out until it forms a rectangle about 8 inches long. Place in the refrigerator for at least 15 minutes before the next step to keep it cold.
Remove the dough from the fridge and lay out onto a lightly floured surface. Place the cold butter in a diaganol inside the dough. Fold the corners of the dough towards the center of the butter, being sure to cover all of the butter with the dough.
Roll out the dough once again to the large rectangle. Fold into thirds and then fold in half to form a square. Wrap the square in plastic wrap and place in the refrigerator for 1 hour.
Repeat the step of rolling out the dough, folding in thirds and then half two more times with one hour in the refrigerator between each roll and fold session.
Roll out the dough one last time. Slice in half and then make 3 inch marks along the dough. At the 3 inch mark slice from one end to the other, forming a triangle.
Roll each triangle from the large end to the point and place point side down onto a parchment lined baking sheet. Cover loosely with plastic wrap and allow to proof for 1 hour.
In a small bowl whisk together the egg white and milk and carefully brush along the tops of the croissants.
Bake in a 375º F oven for 15 minutes until golden brown.