Preheat the oven to 350°F and line 2 baking sheets with parchment paper or spray with non-stick spray. (To get best results, use parchment paper)
In a medium bowl, sift the dry ingredients: flour, baking soda and salt together or you can whisk together as well.
In another large bowl, using an electric mixer at medium speed, beat together the butter, and sugars until smooth and mixed together well.
Add the egg and vanilla and mix on low speed until mixed in.
Gradually add the flour mixture and mix in until just incorporated. Do not keep mixing - do not overmix.
Add chopped white chocolate bar or white chocolate chips and pistachios and stir with a wooden spoon, again no overmixing, just until incorporated.
Using a small or large ice cream scoop or heaping tablespoon, drop the dough onto the prepared baking sheets, 6 to 8 per pan, depending on size you are making. Top with more white chocolate and pistachios if desired.
For extra thick cookies, chill scooped cookie dough balls for 15 minutes or flash freeze for 5 minutes the scooped dough balls on a baking sheet or platter. Especially do this if your cookie dough is warm, so cookies don't spread.
Bake the cookies, 1 sheet at a time, until the bottoms and edges are lightly browned and the tops feel firm when lightly touched,
Small cookies bake 8-10 minutes
Large cookies bake 10-13 minutes.
Let the cookies cool for 5 minutes on the baking sheets, then transfer the cookies to wire racks to cool completely.
Makes 18 -30 cookies depending on size.