Preheat oven to 350°F / 180°C and line a baking sheet with parchment paper.
Roughly chop the pistachios and set aside until needed.
Melt the butter in the microwave in 30-second increments.
Pour the melted butter into a bowl with the sugar and pistachio paste. Stir everything together until combined.
Add the egg and vanilla and stir until combined. If you want to add the almond extract as well, add it now.
Add dry ingredients, including flour, baking powder, baking soda and salt and mix everything together until a soft dough forms.
Add white chocolate chips and about ⅔ of the chopped pistachios and stir into the dough until they are evenly distributed.
Take walnut-sized scoops of dough and roll them with your hands to form balls.
Press the top of each cookie dough ball into the remaining chopped pistachios, then place onto the baking sheet, with plenty of space in between each ball.
Bake for 10-12 minutes, or until the edges start to turn golden brown.
Remove from the oven and let the cookies sit on the baking sheet for at least 10 minutes before transferring them to a wire rack.
Notes
Pistachio Paste - You can either buy this readymade or use my easy recipe to make your own pistachio paste at home. You may want to make the cookies in batches on two baking sheets, so while one batch is cooling on the baking sheet, the next one can be in the oven.