Day 1 – Evening

Feed Your Starter

1. Mix your water and flour with a tablespoon of your existing starter until you have a firm but “stir-able” dough. It should become relatively hard to stir towards the end of mixing. This is to give you a really strong starter that will stay active for hours. So you don’t have to schedule your day around your sourdough’s activity.

Make the Tangzhong

1. In a saucepan whisk together your flour and milk for the Tangzhong. Set to medium heat and keep whisking. The mix will first look very liquid and then form up all of a sudden. Do not take your eyes off it and keep whisking until you have a paste the consistency of creamy potato mash.
2. A whisk should leave a visible trace that doesn’t fill in for a few seconds. I doubt cook 20 seconds longer rather than shorter.
3. Take off the heat and transfer immediately to your stand mixer bowl.
4. Once cooled a little, you’ll be able to touch it without anything sticking to your fingers. That’s how you know you have the right consistency.
5. Cover and allow to cool overnight while your sourdough is becoming nice and active.

Mixing The All-Purpose Enriched Dough

Blend Liquids and Protein

1. For the smoothest result and easiest mixing add Eggs, Greek yogurt, whey protein, Oil and Sugar to a blender. Blend until smooth.
2. Stir in your sourdough starter. In theory you could blend that in too, but I felt my blender was already pretty full

Mix The Dry Ingredients

1. Add the salt and flour to the bowl with the Tangzhong and stir the dry bits briefly.
2. Pour your protein blend into the mix and allow a stand mixer to knead on low speed the mix until you have a very wet and shaggy dough that is well mixed.
3. Add the cold butter in pieces and continue to knead on low speed until the butter is fully incorporated. Scrape down a sides of the bowl a few times, to make sure everything is well mixed and there is no Tangzhong left at the bottom of the bowl.
4. Once you have a very smooth dough that looks way too wet at this point, cover the bowl and allow it to rest for about 30 minutes to 1 hour.

Bulk Proof and Coil folds

1. Starting after about 30 minutes to one hour (this is very flexible) do 3 sets of coil folds by using wet hands to push under the dough, pulling the whole dough up and letting it sink down folding over itself.
2. Turn the bowl by 90 degrees and repeat. Do this 3-4 times or until the dough looks visibly smoother.
3. Cover again and repeat after about 30 minutes. Repeat 2 more times.
4. Your dough should now look very smooth and be less sticky. If not, repeat the above once more.

Put into rectangular or square container (optional)

1. I put my dough into an oiled rectangular box that has a lid, as I find it much easier to portion a dough from that shape than a round one. But that is purely personal preference.
2. Pat it out with your hands a bit, pushing it into the corners.
3. Cover and allow to bulk ferment.
4. I usually let it sit on my counter for a few hours (6-8 hours for this enriched dough.) until visibly risen and then move it to the fridge.
5. For this super buttery dough fridge time is mandatory to firm up the butter, so you can shape it easily. Otherwise it will be way too soft.
6. But depending on your schedule you could also put it into the fridge to cold ferment for up to 3 days of fridge time total. Shape and finish the rise when you have about 8 hours until baking.

Prepare Your Loaf Pans

1. Grease your two loaf pans with a little butter. This will help your baking parchment stick in it and make placing the dough so much easier than wrestling loosely lying parchment!
2. Cut a piece of baking parchment as wide as your pan is long.
3. Place inside the buttered loaf pan and fold the overhanging sides. This will give you an easy way to lift out your sourdough protein brioche later.
4. If you like your crust slightly crisp and gold, lightly butter the parchment too.

Shaping Your Brioche

1. Take your now cold and firm dough out of the fridge and tip it onto a lightly floured work surface.
2. Cut into 16 equal pieces.
3. I used food scales to get them (near) perfectly even, but you can absolutely eyeball it.
4. Now locate the smoother side of each piece (the one that was on top and hit the floured surface usually) and turn that down, so you have the sticky side up. Pat it out lightly using your hand, then grab the four corners, pulling them up and squishing them together in a sort of garlic bulb/dumpling shape.
5. Flip over, so the sticky ends are now on your work surface.
6. Cup your hand over it, barely touching the surface and start moving it in rapid small circles around the bun, until it has enough surface tension to be smooth and “stand up” a little bit.
7. This works best if there is no flour on that part of the surface, so the dough can hold onto it a little. There will be little bits of dough sticking to the worktop. That’s fine.
8. If it’s unworkable or spreads too much it’s likely too warm.
9. Though if even cooling it fully overnight didn’t fix it, you can add a little more flour at this point.
10. Now place 8 dough balls in each loaf pan. They should look pretty closely squished together, so they rise up, giving you a super high and puffy end result.

Final Rise

1. Tuck the loaf pans into plastic bags and close them with a knot or a clip. This will prevent the dough from drying out in the rather long rise it needs.
2. Allow to rise for 6-8 hours at room temperature (my kitchen is about 70°F/21°C and it needed a full 8 hours) until it looks really puffy and risen.
3. To check if your dough is ready gently poke it with an oiled finger (this dough sticks!). It should leave a dent, feeling noticeably airy, that springs back slowly.

Bake Your Brioches

1. Preheat your oven to 350°F / 175°C with an oven rack in the center.
2. Crack an egg into a small bowl and whisk until smooth with a fork
3. Take the loaf pans out of their bags and brush the top of the brioches with the egg wash for that deeply golden, shiny top.
4. Bake for 25-35 minutes or until golden and baked through
5. I like to check the core temperature with an instant read thermometer. It should be 190°F/88°C to be fully baked.
6. Note that bread with protein powder browns a little faster due to the added milk sugars. But that doesn’t mean it’s baked through. So if you are used to non-protein bread, be sure to leave it a little longer, as the enriched dough needs time to bake fully.
7. If you have no thermometer, you could light the bread gently out of the pan and tap the bottom. It should sound hollow when baked through.
8. Once it’s fully baked allow it to cool for about 10 minutes in the pan, then, using the parchment edges to lift it up, gently place it on a cooling rack to cool for another 20 minutes or so.