Step 1: Combine 4 cups all-purpose flour, 1/2 cup warm water, 1/2 cup warm milk, 1/4 cup sugar, 2 1/4 tsp yeast, and 1 1/4 tsp salt. Knead into a dough, cover, and chill for 2 hours.
Step 2: Create a butter block by flattening 1 1/2 cups of chilled butter into a 7x7 inch square between parchment sheets. Chill until firm but pliable.
Step 3: Roll the dough into a 10x10 inch square. Place the butter block in the center at an angle, fold the dough corners to the middle, and seal.
Step 4: Roll the dough into a long rectangle and perform a letter fold. Chill for 30 minutes. Repeat this turning and chilling process two more times.
Step 5: After the final chill, roll the dough to 1/4 inch thickness and cut into 12 long triangles.
Step 6: Roll each triangle up from the base. Proof on a baking sheet for 2 hours in a cool area.
Step 7: Brush with egg wash and bake at 400°F for 10 minutes, then 375°F for 10-15 minutes until golden.