Dissolve the yeast into 2-3 spoonfuls of lukewarm milk, stir in a little flour to porridge consistency and leave the mixture in a warm place to rise for approximately 1 hour.
In a large mixing bowl, beat the butter with the sugar until white, break the eggs one by one, add the mastic, the mahlab and the milk and gradually blend in the flour, constantly kneading until the dough is smooth and non-sticky.
Cover the dough and set aside in a warm place to rise for at least 2 hours. When the dough doubles in bulk, roll it into 9 strips and shape into 3 3-strand braids spreading grated chocolate in between the strips.