Make the cookie dough : Preheat oven to 350F with a rack in the upper and lower thirds. In a medium bowl, using a hand mixer or by hand with a rubber spatula, beat the butter and sugar together until light and fluffy. Add the egg and extracts and beat until homogenous. Add the baking soda, salt, and pistachio flour and mix until combined. Finally add the flour and mix until just incorporated. Set aside.
Make the pistachio chunks: In a microwave, melt the white chocolate. Add the pistachio spread and stir to combine. On a parchment-lined tray, spread the mixture out. Freeze until hard, about 10 minutes. Transfer bark to a cutting board and cut into large chunks. Transfer chunks back to cold tray so they don’t melt. Add about half of the chunks to the cookie dough and mix in.
Bake: Use a large ice cream scoop to portion out cookie dough onto 2 parchment-lined baking trays. Space evenly. Top dough balls with remaining pistachio chunks, chopped pistachios, and flaky salt. Bake for about 12 minutes, switching the trays halfway through cooking, until the cookies are golden brown around the edge. Slam the trays down onto your counter to deflate the cookies. Let cool on the trays. Cookies are best consumed within 3 days stored at room temperature in a sealed container.
