PISTACHIO BUTTER COOKIES

Steps:

• Pour 1/2 cup of the pistachios into a food processor and process until finely ground. With the motor running, start pouring in 1 tablespoon of the vegetable oil in a thin stream through the food processor's opening, stopping when the ground pistachios turn into a paste, and adding more oil if needed. Scrape the pistachio butter into a bowl.
• Coarsely chop the remaining 1/4 cup of pistachios.
• With an electric stand mixer fitted with the paddle attachment or a hand mixer, beat the butter and brown sugar on medium speed until incorporated. Beat on high spread until very smooth, 1 to 2 minutes. On medium speed, beat in the egg yolk and vanilla until well blended, scraping down the sides of the bowl if necessary. Beat in the pistachio butter until thoroughly blended.
• In a medium mixing bowl, whisk together the flour and baking soda. With the electric mixer on low speed, slowly add the dry ingredients to the pistachio butter mixture until there are no patches of flour. Add the chopped pistachios and mix until thoroughly combined.
• Divide the dough in two. Transfer half the cookie dough to a large sheet of plastic wrap on your work surface and form it into a 7-inch log, using the plastic wrap to help roll and shape it. Wrap it in plastic wrap, twist the ends, and refrigerate for 30 minutes, or until firm. Repeat with the other half of the dough.
• Preheat the oven to 350°F. Line a baking sheet with parchment paper, and position a rack in the middle of the oven.
• When the logs are firm, set them back on your work surface, and use a sharp knife to cut the dough into 1/2-inch pieces. (You should have about two dozen.) Set as many of the cookies as you intend to bake about 2 inches apart on the prepared baking sheet.
• Bake for 12 to 15 minutes, rotating the baking sheet front to back halfway through cooking, until they are lightly golden and the edges have started to darken.
• Remove from the oven and let the cookies cool for a few minutes on the baking sheet, then transfer to a rack to finish cooling.
• Put the remaining cookies on a second baking sheet and transfer it to the freezer.
• Freeze the cookies for at least an hour, until they are hard. Remove the baking sheet from the freezer and put the cookies in a freezer-safe heavy-duty resealable plastic bag, rolling out the excess air before you seal it. Return to the freezer and store for up to 3 months. Bake the frozen cookies for 15 to 20 minutes, until lightly golden.