Makes about 14 croissants.
Ingredients:
150g fed start
450g flour
5g salt
50g softened butter
210g warm water
50g sugar
1 cup cold butter
1 egg for egg wash
Dough: Combine all ingredients except the cold butter and egg in a large bowl. Once the dough starts to form a ball, transfer the dough to a flat surface and knead for 5 minutes. You may need to use a bench scraper for the first bit until dough starts to be less sticky. I promise it will come together! Transfer the dough back to the bowl and cover with plastic wrap. Let it rise until it has doubled in size. I left mine on the counter overnight. Once it has doubled place the bowl in the fridge so the dough can get cold, at least 30 minutes. Once you put it in the fridge the dough rises much more slowly so I actually left mine for a few hours. Keep it covered with plastic so it doesn't dry out.
Butter insert: Fold a piece of parchment in half, hamburger style. Slice the cold butter thin and lay in flat on one half of the folded parchment. Fold the other half over the top of the butter. Use a rolling pin to make it one large sheet. Place in the fridge until the dough is ready.
Note: Try not to handle the dough too much. If the butter in the insert gets too warm you will not get flaky layers. Sprinkle a flat surface with a little flour, doing this any time the dough starts to feel sticky. Try not to use too much flour. Roll out the cold dough just over 2x the width and 1x the height of the butter insert. Lay the butter on one half and fold the dough over the top. There should be just enough dough to seal the edges around the butter. Roll the dough to about 15 inches long. Width doesn't need to change. Letter fold the dough, bringing the bottom of the dough 1/3 the way up and the top of the dough back down over the top of it to meet the new bottom. Rotate the dough 90 degrees so you are rolling the long side longer, hopefully that makes sense! The letter fold should happen on alternating sides. Roll out the dough to 15 inches long again, repeat the letter fold. Wrap the dough in the parchment used for the butter insert and refrigerate for one hour.
Remove the dough from the fridge and roll it out to 15 inches long. Letter fold the dough. Remember to rotate the dough 90 degrees between letter folds. Roll it out again and letter fold again. Wrap the dough in the same parchment and refrigerate for one hour. Remove the dough from the fridge and roll it out to 24 inches by 15 inches. If you can't get the dough to get any bigger follow this step: Once the dough seems like it isn't getting any bigger, place it on a baking sheet with parchment and cover with a damp cloth. Let it rest in the fridge for 15 minutes or so then roll it some more. Sometimes the dough just needs to relax a bit.
Using a pizza cutter slice into triangles. The base of mine were about 3 inches. Add a notch in the center of the wide end, this makes it easier to roll. Roll each triangle into a croissant shape, starting at the wide end. Set each roll onto a parchment lined baking sheet. I did 8 on one sheet and 6 on the other. Cover each pan with a damp bread towel and let the croissants rise to double, they should jiggle when you shake the pan. This step takes several hours, so check them periodically and spray with a spray bottle if they seem dry. Preheat the oven to 375 degrees. Brush each one with egg wash: 1 egg beaten with a splash of water. Bake for 20-25 minutes or until very golden brown.
