125g whole eggs (around 4 large eggs, weigh with shell on)
125g butter in chunks
30g sugar
1 teaspoon salt
4g active dry yeast, or 10g fresh (about a teaspoon of active dry yeast)
3-4 tablespoons orange blossom water (to taste)
1 egg, beaten, for the glaze
Instructions
If using active dry yeast, re-activate the dry yeast in a few spoonfuls of 38°C water. Wait 10 minutes.
Mix the salt, flour, sugar and yeast (start with the salt to make sure it's well spread through the flour before adding the yeast). Add the eggs a few spoonfuls at a time, making sure they're well incorporated. Then add the butter in 6-7 chunks--same, make sure it's well incorporated in the dough before continuing.
Do five stretch and folds on the counter at five-minutes intervals to give the dough some shape.
Then start the room temperature rest: put the ball of dough under a salad bowl and leave it for a bit. Every half-hour, give the dough another stretch and fold, and cover again with the salad bowl.
Get a clean salad bowl (or clean the previously used one). Oil it, then shape the dough into a round. Cover with cling film or a food-grade plastic bag, stick into the fridge, and leave to rest for at least 15 hours.
Get the dough out. Butter and flour the inside of a rectangular mould. Shape it into three balls. Leave to rest in a warm place (like an oven that's just been turned off--just remember yeast dies above 60°C so by "warm" I mean more like 25°-27°C) until doubled in size. Given that the dough is cold this actually takes 3-4 hours. See attached picture for an idea of what it looks like.
Pre-heat oven to 190°C.
Beat the remaining egg, and glaze the top of the brioche with it. If your mould isn't non-stick, be careful where you put your glaze: you can very easily glue the brioche to the mould if you go too wide when glazing...
When the oven is warm, stick the mould in it. Cook for 20-30 minutes, until golden and risen. Take the brioche out of the mould and leave it to cool on a wire rack.
Recipe by Aliette de Bodard at https://www.aliettedebodard.com/recipes/brioche/