To make the croissant dough, combine the active sourdough starter, sugar, salt, melted butter, whole milk, and flour together in a large bowl. Mix until a shaggy dough, then turn out on a clean surface to knead 4-5 minutes. The dough should be smooth and pliable.

Place in a greased bowl and cover to rise in a warm environment for 4-5 hours, until doubled in volume.

Place the dough in the fridge overnight, about 8-12 hours.

To start the laminating process, use a sheet of parchment paper to measure out 6x8” rectangle. Fold the parchment so that you can use it to roll out the butter.

Slice each butter stick into 3 pieces lengthwise. Place in an even layer in the parchment rectangle, cover, and roll out to meet the 6x8” dimensions. Set aside away from direct sunlight or heat.

Take out the chilled dough and roll out on a well-floured surface to 13x9” rectangle.

Add the butter rectangle in the center of the dough long ways. Fold in the outer two flaps of the dough and pinch all ends together to seal it in.

Using a rolling pin, gently pound the dough horizontally, then vertically, then gently roll out to 24x10” rectangle. Review video for visual guide.

Brush the surface with cold water, then fold in the two ends like an envelope to meet at the center, then fold again lengthwise like a sandwich. Cover and place on a flat plate to chill in the fridge 30 minutes.

Repeat the process of lightly pounding and rolling out 24x10” rectangle, then folding the exact same way as last time. Except cover and chill 1 hour this time.

Let the dough rest 20 minutes (during winter/fall) or 10 minutes (during summer months) on the counter away from direct heat or sunlight.

On a very floured surface, roll out to 18x12” rectangle. Use a pizza cutter or serrated knife to trim the edges.

Slice the rectangle into 8-10 equal-sized triangles, about 2-3” wide at the top portion. Roll up tightly, gently stretching at the triangle tips as you get closer to the end.

If adding the ham and cheese, place at the large end of the triangle and roll up tightly.

Place the croissants on a parchment paper lined baking pan. Cover lightly with plastic wrap and set aside to rise until doubled in size and wiggly, about 2-4 hours.

Preheat oven to 425F.

Brush the croissant with an egg wash and garnish with flaky salt (if desired) to bake in the middle rack for 15-18 minutes, until deeply golden on top.

If you want to bake the next morning, simply store in the fridge overnight and let rest on the counter 2 hours prior to baking the next morning. Enjoy!

Day 1 @ 5:00pm – Make croissant dough

Day 1 @ 9:00pm – Put away dough in fridge overnight.

Day 2 @ 9:00am – Start the process of laminating the dough.