Prepare Pie Crust: Prepare your pie dough before beginning. Make pie dough the night before because it needs to chill in the refrigerator for at least 2 hours before rolling out and blind baking.

Roll Out the Chilled Pie Dough: On a floured work surface, roll out one of the disks of chilled dough. Turn the dough about a quarter turn after every few rolls until you have a circle 12 inches in diameter. Carefully place the dough into a 9-inch pie dish. Tuck it in with your fingers, making sure it is completely smooth. Fold the excess dough back over the edge and use your hands to mold the edge into a rim around the pie. Crimp the edges with a fork or use your fingers to flute the edges. Chill the pie dough in the refrigerator for at least 30 minutes and up to 5 days.

Partially Blind Bake: Preheat oven to 375°F (190°C). Line the chilled pie crust with parchment paper and fill with pie weights or dried beans. Bake until the edges of the crust are starting to brown, about 15-16 minutes. Remove pie from the oven and carefully lift the parchment paper (with the weights) out of the pie. Prick holes all around the bottom crust with a fork. Return pie crust to the oven and bake for 8 minutes to help set the bottom. Brush egg wash/egg white all over the bottom and sides of the warm pie crust. Set pie crust aside.

Reduce Oven Temperature: Reduce oven temperature to 350°F (177°C).

Make the Brownie Batter: Melt the butter and whisk in the oil and granulated sugar. Let it sit for 3-5 minutes to slightly cool. Whisk in 2 whole eggs, 1 egg yolk, and vanilla extract until combined. Add the cocoa powder, flour, and salt and whisk until combined. Batter will be thick. Fold in the walnuts and chocolate chips.

Bake: Spoon and spread the batter evenly into crust. Bake for 40-45 minutes or until a toothpick inserted in the center comes out with just a few moist crumbs. If the edges of the pie crust are browning too quickly, apply a pie crust shield or a ring of aluminum foil to protect it. The brownie filling will set as it cools.

Serve: Cool for 20 minutes before slicing and serving. Tastes best served warm!