In a mixing bowl, stir together the graham cracker crumbs, melted butter, and brown sugar until all the crumbs are coated with butter and the mixture resembles wet sand.
2½ cups graham cracker crumbs, 6 tablespoons butter, 2 tablespoons packed light brown sugar
Press the crumbs into a lightly greased 9-inch pie plate, making sure to firmly and tightly press the crust in. Place the crust in the freezer for 20 minutes.
In a separate mixing bowl, whisk together the instant pistachio pudding mix and milk until the pudding starts to thicken. Let it sit for 3-5 minutes so it can thicken even more.
1 box (3.4 oz) instant pistachio pudding mix, 1½ cups 2% milk
In a large mixing bowl, using an electric hand mixer, beat the cream cheese until smooth and lump-free. Add in the thickened pistachio pudding and mix until combined.
1 bar (8 oz) cream cheese
Add in the Cool Whip and beat on low speed until thoroughly combined.
8 ounces Cool Whip
Evenly spread the pie filling into the pie crust and smooth out the top of the pie. Cover the pie with a lid or plastic wrap, and refrigerate for at least 6-8 hours, but overnight is preferred.
When ready to serve, top the pie with additional whipped cream (homemade or store-bought) as a second layer to the pie OR you can pipe it around the outer edges for a more decorative look. Add some chopped pistachios and enjoy!
additional whipped cream, chopped pistachios