In the bowl of an electric stand mixer, cream together unsalted butter, granulated sugar, lemon zest, and salt. Beat them on medium speed until the mixture is light and fluffy, which usually takes about 2 to 3 minutes. Make sure to scrape down the sides of the bowl to ensure everything is well incorporated.
Next, mix in fresh lemon juice and vanilla extract. Continue to beat until these ingredients are fully combined with the buttery mixture.
Now, it’s time to add in the dry ingredients. Gradually add the all-purpose flour and mix on low speed until just combined. At first, the dough will look sandy, but don’t worry! Keep mixing, and soon it will come together into a smooth dough.
Scoop the dough out onto a lightly floured surface. Use your hands to compress the dough, ensuring there are no air pockets. This step is crucial for achieving a consistent texture in the cookies.
Shape the dough into a log about 10 inches long. Make sure the log is even and smooth all around for uniform baking.
Wrap the log in parchment paper or plastic wrap, then chill in the refrigerator for about 2 hours or until firm. Chilling the dough helps the cookies keep their shape while baking.
During the last 15 minutes of chilling, preheat your oven to 350 degrees Fahrenheit (175 degrees Celsius). This way, your oven is perfectly hot when your dough is ready to go.
Once the dough has chilled, remove it from the refrigerator and slice it into 1/3 inch thick cookies. Transfer 12 slices at a time onto an ungreased baking sheet, leaving some space between each cookie.
Bake the cookies in your preheated oven until the bottoms are lightly golden and the cookies are set, about 13 to 16 minutes. Keep an eye on them, as oven times can vary.
After baking, let the cookies cool on the baking sheet for about 10 minutes before carefully transferring them to a wire rack to cool completely. This step allows them to firm up and makes handling easier.
Once the cookies are completely cool, melt the vanilla candy melts or white chocolate in a microwave-safe bowl. Heat in 30-second increments, stirring well between each, until the chocolate is smooth and melted.
Dip half of each cookie into the melted chocolate, allowing any excess to drip off. Then, transfer them to a parchment-lined sheet. Sprinkle the tops with chopped pistachios before the chocolate sets for a lovely garnish.
Finally, let the cookies set completely at room temperature before storing them in an airtight container. These treats can be enjoyed for days!
