1. In a small saucepan, combine the milk, sugar, and eggs. Place it over heat and whisk until the mixture is lukewarm, about 36-40 degrees Celsius. Be careful, if the mixture gets too hot, it will 'kill' the yeast. In the bowl of a stand mixer, add the flour, salt, mahlab, mastic, cardamom, and yeast, then mix. Pour in the milk mixture and knead well.
2. When you've reached 70% of the kneading process, add the softened unsalted butter spoonful by spoonful. Knead on medium speed for 20 minutes. Cover the bowl with plastic wrap and set it aside for 4 hours to rise. To make it rise faster, cover it with a towel. Alternatively, for a quicker rise, preheat your oven to 35-40°C and place the covered mixer bowl inside. It will have risen in 1 ½ -2 hours. One way to check if the dough is ready is to place a small round piece of dough in a glass of water. When it floats to the surface, it's ready. Keep this glass next to the dough. If you choose to let the dough rise in the oven, place the glass in the oven as well.
3. When the dough has risen, uncover it and fold it. This means bringing the edges towards the center and kneading it lightly. Cover the bowl again with plastic wrap and let it rise for another 1 – 1 ½ hours. Alternatively, place it covered in the oven for about 1 hour, and if you wish, repeat the trick with the glass of water and dough. When the dough has risen, remove it from the bowl and divide it into 3 pieces. Shape each piece into a log and cut 3 pieces of 200-220g each. Knead them well.
4. For each tsoureki, you will need 3 pieces of dough. Place them in front of you. Take one piece of dough and roll it into a small strand. Repeat with the other two. Then, take the first strand and roll it into a long strand, 40 cm in length. Repeat with the remaining strands. Stretch them out gradually, because if you try to stretch them into long strands right away, it will be difficult. Place them vertically, one next to the other. Join the ends of the middle and left strands to the first one. Create a fairly tight braid. Start with the strand on the right and bring it over the middle one. Then, do the same with the left strand. Repeat this process until the tsoureki is complete. Tuck the ends from the top and bottom inwards so the tsoureki doesn't unravel.
5. Place the tsoureki on a baking tray lined with non-stick parchment paper. Once all 3 tsourekia are braided, cover them with a towel or plastic wrap and set them aside for 1 – 1 ½ hours to rise, or continue the rising process in the oven preheated to 35-40°C, repeating the trick with the glass of water and dough. When they are ready for baking, brush them with the egg wash. Brush them twice with the egg wash for a beautiful golden-brown color. Sprinkle them with the sliced almonds. Bake in a preheated oven at 180°C for 25-30 minutes. Remove the tsourekia from the oven and let them cool. Store the tsourekia by wrapping them in plastic wrap.
