# What You'll Need:
→ Dough
01 - 2 cups bread flour
02 - 1/4 cup granulated sugar
03 - 2 teaspoons fine sea salt
04 - 1 cup whole milk, cold
05 - 1/2 cup active sourdough starter at 100% hydration
06 - 2 tablespoons unsalted butter, softened
→ Butter Block
07 - 1 cup plus 2 tablespoons unsalted butter, cold
→ Egg Wash
08 - 1 large egg
09 - 1 tablespoon whole milk
# Steps to Follow:
01 - In a large bowl, combine bread flour, granulated sugar, and fine sea salt. Add cold milk, active sourdough starter, and softened butter. Mix until just combined, then knead for approximately 8 minutes until smooth and elastic dough forms.
02 - Shape dough into a rectangle, wrap with plastic wrap, and refrigerate for at least 2 hours.
03 - Place cold butter between two sheets of parchment paper. Pound and roll into a 8 by 6 inch rectangle. Chill until firm but still pliable.
04 - On a lightly floured surface, roll out dough to a 16 by 8 inch rectangle. Position butter block on one half, fold dough over, and seal all edges.
05 - Turn dough 90 degrees and roll into a 24 by 8 inch rectangle. Fold into thirds in letter fold style, wrap in plastic, and chill for 1 hour.
06 - Repeat the rolling and folding process two additional times, chilling for 1 hour between each turn to allow gluten relaxation and butter firmness.
07 - After the final fold, wrap dough and refrigerate overnight for 8 to 12 hours to develop flavor and ensure proper lamination.
08 - Roll dough to a 24 by 12 inch rectangle approximately 1/5 inch thick. Cut into 12 long isosceles triangles with a sharp knife.
09 - Starting from the wide base of each triangle, roll tightly toward the point, then curve into a crescent shape and tuck the tip underneath. Arrange on parchment-lined baking sheets.
10 - Cover loosely with a cloth and proof at room temperature until doubled in volume, approximately 2 to 3 hours.
11 - Set oven temperature to 400°F and allow to reach full temperature.
12 - Whisk together egg and milk until combined. Using a pastry brush, apply a light, even coating to each croissant surface.
13 - Bake for 18 to 22 minutes until golden brown with crisp exterior. Transfer to wire rack and cool slightly before serving.