Use an electric mixer on medium speed to mix butter, oil and sugar. Add flour, baking powder, and water and mix on medium speed. The dough should be a soft, pliable consistency. Cover the dough with plastic wrap and set it aside for thirty to forty-five minutes at room temperature.
For the Filling:
Combine dates, butter, hot water, sugar, and cinnamon in a separate bowl and mix on medium speed until well combined.
Flour a work surface to prevent the dough from sticking. Roll out dough until about 1/8-inch thick. Use a two-inch round cookie cutter or a water glass to cut out a circle shape. Place one rounded teaspoon of date filling in the center of each circle shape. Fold into a half-circle shape. Using a fork, gently press the edges together to seal.
Preheat oven to 350 degrees. Lightly spray baking sheets with cooking spray (or line of parchment paper).
Place cookies on baking sheets. Brush each cookie with egg wash. Bake for 15 - 20 minutes. Cookies should be golden, not brown. Lift cookies with a spatula and place them on cooling racks.
Makes about two - three dozen cookies. Enjoy!
I found I only needed half of the filling for all of the dough. 1-1/2 pounds of dates (without pits) was too much.
I love the look of sparkling sugar on cookies, so sprinkled a bit on some of the cookies after I applied the egg wash.