To prepare the clarified butter: In a medium-sized saucepan, melt butter over low heat without stirring for 10 to 15 minutes, allowing the milk solids to separate from the fat. Remove the saucepan from the heat, let the butter stand for 5 minutes, then skim off the foam from the surface. Gently pour the yellow liquid into a separate bowl, leaving the milk solids in the pot.
In a medium-sized bowl, mix the dry ingredients: flour, baking powder, milk powder, mahlab powder, salt, and sesame seeds until fully combined.
Add the clarified butter to the dry ingredients and mix well until the mixture is evenly coated. Gradually mix with vanilla, continuing to mix until the dough comes together.
Roll each piece of dough into a ball.
If making filled cookies, prepare the date filling by mixing pitted dates, butter (or ghee), and cinnamon powder until well combined.
If adding filling, press the centre with your thumb to create an indentation, add the filling, then enclose it with the dough, ensuring it is completely sealed.
Place the dough balls on a silicone mat or parchment-lined baking sheet, spaced an inch apart.
Bake for 18 to 22 minutes, or until the tops are blonde and the bottoms are light golden brown. Avoid over-baking, especially for filled cookies, to prevent the fillings from hardening.
Allow the cookies to cool on the baking sheet for a few minutes, then transfer them to a wire rack to cool completely.
Once cooled, dust the cookies with powdered sugar using a small sieve or roll them in a bowl of sugar to coat.
Serve or store the cookies in an airtight container. They will keep well at room temperature for several weeks.