In a small saucepan, add the milk, water, sugar, and half the amount of butter (100 grams).
Warm up the mixture over medium heat by whisking constantly. Remove from heat, once the butter and sugar have dissolved completely.
Add the yeast (make sure the mixture is under 60° C before doing so), the vanilla extract, the orange zest, and the mahleb powder. Whisk until fully combined.
Pour the mixture into the mixer's bowl, along with half the amount of flour.
Beat over medium speed for 2 minutes (with the mixer's dough hook attached on).
Add the eggs one at a time until fully incorporated.
Add the remaining flour slowly.
Once the dough is fully combined remove it from the mixer. It should all come out in one piece. Otherwise, add a bit more flour.
Add the dough to a large mixing bowl and cove the bowl r with a dampened kitchen towel.
Let the dough rest at room temperature for a few hours until it doubles in size. It takes about 2-3 hours at an average temperature of 20 to 25 ° C.
Take the dough and press it down with your hand to remove the air.
Melt the remaining 100 grams of butter and wait until it cools down a bit. Then start to pour the butter to the dough (small bits at a time) while kneading.
Continue kneading until all the butter is incorporated into the dough. It may look a lot but don't worry it will absorb it all. Just keep kneading. You will feel the dough become very soft and airy.
Preheat oven to 50 ° C for 10 minutes. Add a small pan with some water at the bottom of the oven.
Cover the dough with a tea towel. Turn off the oven and add the bowl with the dough in the oven. Let the dough rest for 30 minutes.
Once the dough has doubled in size once more remove from the oven.
Squeeze the dough to remove the air and cut it in half. Then cut each piece to either 2, 3 or 4 pieces. Depending on how many pieces you want your braid to be made of.
On a lightly floured surface, shape each piece into a long cord. Pinch the desired number of cords together at one end. Start making the braid. Once you're finished, pinch the other end together as well. Tuck it under the braid to secure it.
Transfer each Tsoureki on a large baking pan or your ovens tray covered with parchment paper.
In a small mixing bowl, whisk the egg with the one tablespoon of water. Brush the Tsoureki with the egg wash and add some flaked almonds on top.
Preheat oven to 50 ° C once more for 10 minutes. Turn off the oven. Add the Tsoureki and let it rest for 20 minutes.
Remove the Tsoureki from the oven. Preheat the oven to 150 ° C / 302°F. Bake the Tsoureki for approximately 40-45 minutes. Preferably one Tsoureki at a time and without removing the pan with the water from the bottom of the oven.