You can use a food processor to cut up your dates, chop your roasted pistachios, or use a knife and a cutting board. Cut the dates into small pieces and the same for the roasted pistachios.
Zest 1 or 2 oranges (depending on the size of the orange) to get 2 tablespoon of orange zest. Set this bowl aside.
Weigh or measure the powdered sugar into a bowl and set aside. In a separate bowl, weigh or measure the flour, baking powder, and salt together. I take a whisk and blend them.
In a stand mixer or handheld, add the butter and mix on medium speed to cream the butter. Make sure all the butter has been creamed.
Turn the mixer speed down and slowly add the powdered sugar until it is all incorporated. Turn the mixer back to medium speed and mix for 2 minutes. Next, add the vanilla extract and orange zest and blend. I had to stop and scrape down the bowl and across the bottom to ensure it was all mixed.
Turn the mixer speed down and slowly add the flour mixture. Don't over-mix. Turn the mixer off, add the pistachios and dates, and turn the mixer on for about 15 seconds. You may need to hand mix the dough a little to ensure the pistachios and dates go thoroughly through the whole dough.
Put the dough out of the bowl on a silicone pastry mat. Divide the dough in half, roll, and form 2 log shapes, about 12 inches each. It should have a diameter of approximately 1-½ inches. Wrap each log with plastic wrap and put it into the refrigerator for at least 1 hour. I use a baguette pan to help keep the round log shape.
Preheat the oven to 350°F (175°C or 180°C). Remove one log from the refrigerator and unwrap the plastic wrap from the cookie log. Slice into ¾-inch slices and put them onto a parchment-lined cookie pan. These cookies do not spread much, so they only need about an inch between each disc. Bake for 10 to 12 minutes; leave them on the pan for a minute or two after pulling the pan from the oven before moving to a cooling rack. Wait for the cookies to cool completely before starting the white chocolate.