Mix semolina and flour in a large baking bowl. Knead in the melted butter until everything holds together well. Fold in the orange and rose water and knead together until you have a fairly soft dough. Let the dough rest for an hour.
For the fillings, mix 100 g of sugar with each of the 3 fillings (dates, walnuts, pistachios), divide the rose and orange water evenly among the fillings.
Form the dough into small balls (about 1 tsp. dough/ball). Place these in the center of your left hand, gently press the ball in with your right hand, pour in filling and seal well, rolling again to form a ball. Place the ma’moul on a baking tray and bake at 200 °C until golden brown.
Cool on a baking rack and dust with powdered sugar.
Normally, the ma’moul is not closed by hand but pressed into a wooden mold. Use a different pattern for each filling.