Into the bowl of your stand mixer fitted with the hook attachment, sift 500 g flour, milk powder, baking powder, and mahlab. Mix in the yeast. 

In a small saucepan, stirring constantly, heat the milk, butter, sugar, and salt just till warm (about 49 °C) and the butter is almost melted.

After making sure the milk mixture is not too hot, gradually pour it into the flour mixture with the mixer on low speed, and beat until combined.

On low speed, add the egg and vinegar and knead on medium-high speed for 3 minutes.

Add in more flour as needed. Knead on 2nd speed for about 5 minutes, until you have a soft dough that is smooth and elastic but not sticky.

Let the dough rise in a lightly greased bowl until doubled.

In the meantime, mix the filling ingredients together well.

Deflate the dough gently; divide the dough and the filling into 12 pieces each. Form the dough into balls and let them rest for 10 minutes. 

Roll out a ball of dough into an oval or rectangular leaf (about 0.5 cm thickness). Then form a piece of filling into a log the length of the dough leaf, and place it on the edge of the leaf; roll the dough over the filling and seal. Form it into a ring and seal the ends, then make cuts in the dough with a knife.

Place the breads on 2 baking sheets lined with parchment paper, cover, and let rest for about 30 mins.

Brush with milk, or cream, or egg, and sprinkle with sesame.

Bake at 160 °C fan oven for 2 pans (or 180 °C normal for 1 pan), for about 16–20 mins or until top and bottom are browned.

Allow to cool 5 minutes before transferring from the baking sheet.

Serve warm.