# How to Make It:
01 - In a large bowl, combine bread flour, sugar, and salt. Add cold milk, sourdough starter, and softened butter. Mix until just combined, then knead for approximately 8 minutes until the dough becomes smooth and elastic.
02 - Shape dough into a rectangle, wrap in plastic, and refrigerate for at least 2 hours.
03 - Place 9 ounces cold butter between two sheets of parchment paper. Pound and roll into an 8 by 6 inch rectangle. Chill until firm but pliable.
04 - On a lightly floured surface, roll out dough to a 16 by 8 inch rectangle. Place butter block on one half, fold dough over, and seal edges firmly.
05 - Turn dough 90 degrees and roll into a 24 by 8 inch rectangle. Fold into thirds in a letter fold pattern, wrap in plastic, and chill for 1 hour.
06 - Repeat rolling and folding process two more times, chilling for 1 hour between each turn to allow the gluten to relax and butter to remain distinct.
07 - After final fold, wrap dough in plastic and refrigerate overnight for 8 to 12 hours to develop deep sourdough flavor and achieve proper lamination.
08 - The next morning, roll dough to a 24 by 12 inch rectangle approximately 1/5 inch thick. Cut into 12 long triangles with a sharp knife.
09 - Starting from the wide end of each triangle, roll tightly into a crescent shape, tucking the tip underneath. Place on parchment-lined baking sheets.
10 - Cover loosely with a damp towel and proof at room temperature until doubled in size, approximately 2 to 3 hours.
11 - Preheat oven to 400°F (200°C) to ensure a crisp, golden crust develops evenly during baking.
12 - Whisk egg and milk together in a small bowl. Brush croissants lightly with egg wash using a pastry brush for a golden appearance.
13 - Bake for 18 to 22 minutes until golden brown and crisp. Cool slightly on a wire rack before serving.