Put the semolina, farina, sugar and mahlab in a mixing bowl. Add the melted butter along with the orange blossom water and beat well. Knead the mixture for 3–4 minutes, working it into a pliable dough. Cover with cling film/plastic wrap and chill in the refrigerator for 2 hours.
Meanwhile, prepare the fillings. For the pistachio filling, put the pistachios, sug