FOR THE ROUX:

1. Whisk together the flour & water in a small saucepan – cook over medium high heat, whisking constantly, until thickened (it is ready when the whisk leaves a visible trail as it moves through the roux)
2. Remove from the heat & allow to cool until no longer hot to the touch

FOR THE DOUGH:

1. Place the flour, cream of tartar, sugar, instant yeast & salt in the bowl of a stand mixer and use a handheld whisk to combine
2. Heat the milk with the mahlepi and ground mastiha & sugar mixture until milk is hot but not boiling.
3. Allow the milk to cool and then add the eggs, honey, orange zest & roux to the saucepan, whisking well to combine
4. Add liquid to the flour in the bowl of the stand mixer and mix on low speed with the dough hook until the dry ingredients are incorporated into the wet.
5. Slowly add in the butter, one piece at a time, letting each piece mix into the dough before adding the next piece
6. Raise the mixer speed to high and mix for another 5 minutes. The dough will be quite sticky but relatively smooth & stretchy.
7. Spray a silicone spatula lightly with cooking oil spray and scrape down the sides of the bowl.
8. Transfer the dough to a lightly oiled bowl or proofing bucket large enough for the dough to rise to double its size, and cover with an oiled piece of plastic wrap (or the oiled top to your proofing bucket) Place the dough in the refrigerator for at least 12 hours and up to 5 days
9. On baking day, line a rimmed baking sheet with unbleached parchment paper & set it aside.
10. Remove the dough from the refrigerator and turn it out onto a lightly floured surface – knead the dough until it is smooth
11. To make braided bread, divide the dough into three equally sized pieces (I use a scale to get them identical). Shape each piece into an 18″ long rope & braid the three pieces together (see gif above for reference)
12. Once the loaf is braided, carefully transfer the braided dough, already on parchment paper, to a rimmed baking sheet.
13. Brush the top of the dough carefully but liberally with the egg wash.
14. Cover the braided bread with oiled plastic wrap and allow to rise in a warm, draft-free location for 40 minutes
15. Brush the loaf again with egg wash, sprinkle with sesame seeds and allow to continue to rise uncovered until nearly doubled in size (about another 20 minutes).
16. Place the bread in the center of a cold oven and turn the heat to 350° F. Bake for 20 minutes, then turn down the oven temperature to 325° F and bake until the internal temperature of the bread is 185° F on an instant-read thermometer, about another 15 minutes.
17. Allow the bread to cool completely before slicing, toasting & serving with butter (slice the bread about 3/8″ thick for best results)