Activate the yeast with the water and about half of the sugar, then mix together all the ingredients to form a dough. Knead until smooth (no need to work it very much), then press it into a disc, cover it, and let it rest in the fridge for at least an hour (or overnight)
While the dough rests, use a rolling pin to smash the cold butter between two wax paper sheets until its a square about as wide as your hand is long. You may need to trim the edges, lay them over the center of the butter, and roll it out a few times to get a good, even shape. The important part is to get it to an even thickness all over. Put the butter back in the fridge long enough that it’s nice and solid again.
Take out the dough and roll it into a square big enough that you can lay the butter in the middle of it, turned forty-five degrees. In other words, the corners of the butter square will be in the middle of the sides of the dough square. Fold the dough corners in so that the whole butter square is wrapped up and press and smooth the edges. Rest in the fridge for about 20 mins.
Roll the dough out into a long rectangle, a little less than three times as long as it is wide, and fold the dough up in thirds. Once its folded up, the folded edge should be slightly longer than the open edge. Let it rest for twenty minutes, then turn it a quarter turn and do the same thing again. Repeat the process once more (I usually do it three times, but you can also try four). Let the dough rest for at least an hour, or overnight
Take the dough out and roll it into a very long rectangle (about 20 cm x 100 cm). If the dough is resisting, fold it up and let it rest in the fridge.
Next, use a small knife or pizza cutter to make 7 marks along one of the long edges, dividing it into 8 equal segments. On the opposite edge, you want to make a mark right in the middle of each of the marks on the first side (8 marks total). Use your pizza cutter to connect all the marks, making a zig-zag shape that leaves you with 15 long triangles and two end pieces.
To shape the croissants, take a triangle and stretch it slightly longer (basically as long as you can get it without ripping the dough). Make a short notch in the center of the base of the triangle, then roll them up base to tip.
Apply an egg-wash before proofing. Proof the croissants by putting them in the oven and letting it preheat for about a minute then turning it off. Do this often enough to keep them above room temperature, but not cooking. After 2-3 hours, they should look puffed up and kind of jiggly. Apply a second egg-wash.
Bake them at 400 for about 15 minutes, but start checking them around 10 minutes to make sure they’re not browning too quickly.