In the bowl of an electric stand mixer, beat together the softened butter, granulated sugar, lemon zest, and salt until combined and creamy.

Mix in the fresh lemon juice and vanilla extract, blending well.

Gradually add in the all-purpose flour, mixing until everything is well combined.

Scoop the dough out and compress it with your hands. Shape it into a 10-inch log on a lightly floured surface.

Wrap the log in parchment or plastic wrap, then chill it in the refrigerator for 2 hours.

During the last 15 minutes of chilling, preheat your oven to 350°F (175°C).

Remove the chilled dough from the refrigerator and slice it into 1/3-inch thick slices.

Place 12 slices on an ungreased baking sheet and bake for 13-16 minutes, or until the bottoms are lightly golden.

Let the cookies cool on the baking sheet for about 10 minutes before transferring them to a wire rack to cool completely.

Once the cookies are cool, melt the vanilla candy melts or white chocolate in a microwave-safe bowl in 30-second increments, stirring until smooth.

Dip half of each cookie into the melted chocolate, shaking off any excess, and transfer them to a sheet of parchment paper.

Immediately sprinkle chopped pistachios on top before the chocolate sets.

Allow the cookies to set, then store them in an airtight container at room temperature.