Preheat the oven to 300 degrees Fahrenheit. Line a 9 x 13 x 2-inch pan with aluminum foil or parchment paper for easy removal and set aside.
In a medium bowl whisk together 1 ¾ cups all-purpose flour and ⅓ cup granulated sugar. Beat in 1 cup softened salted butter with a hand mixer on low until combined. Press the crust into the bottom of the prepared pan and bake for 30-35 minutes, or until the crust is lightly golden brown on the edges. Remove from oven and let it cool completely.
While the crust cools, prepare the pistachio layer by beating 8 ounces cream cheese, and 1 cup powdered sugar together with a hand mixer on medium-speed until creamy. Add in ¾ cup milk and 1 (3.4-ounce) box instant pistachio pudding and continue to beat until smooth.
Spread the pistachio cream evenly over the cooled crust and refrigerate for at least 2 hours or until fully set. Top with ½ cup roughly chopped pistachios before removing from the pan to slice and serve.