In a small saucepan over medium-low heat, combine the dates, water, and salt. Cook the dates, mashing and stirring until they have broken down into a paste (about 3 minutes). Let cool.

Preheat the oven to 325°F (165°C) and line two baking sheets with parchment paper. Set aside.

In a mixing bowl or in a food processor, combine the flour, sugar, and baking powder, then pulse or cut the butter in.

Combine the milk and rosewater and then stir into the dough until it comes together.

Gather the dough together, and then divide the dough into 20 equally-sized balls.

Take one ball of dough, flatten it in the palm of your hand and pinch it into a bowl shape.

Place a teaspoon of filling in the center of the dough and bring up the sides and pinch together to seal the filling in.

Roll and flatten slightly, and then place the cookie seam side down on the prepared cookie sheet. Repeat with the remaining dough and filling.

Prick the top of the cookies with a fork or toothpick in a decorative pattern, and then bake until the cookies are just beginning to turn golden, about 25-30 minutes. Dust generously with powdered sugar while the cookies are still warm.

Store cooled cookies in an airtight container at room temperature for up to 3 days.