Make the crust. In a food processor, or mixing bowl combine the flour, sugar, and salt. Scatter the butter over the flour mixture and cut in the butter until the mixture resembles coarse cornmeal. If using a food processor, transfer mixture to large bowl. Sprinkle 3 tablespoons of the ice water over the mixture. Stir and press dough together, using a spatula, until dough sticks together. If dough does not stick together, stir in remaining tablespoon of water. Turn the dough onto a sheet of plastic wrap and flatten into a 4-inch disk. Wrap tightly in plastic wrap and refrigerate for 1 hour.
Roll out the chilled pie dough: On a floured work surface, roll out the disc of chilled dough. Turn the dough a quarter turn after every few rolls until you have a circle 12 inches in diameter. Carefully place the dough into a 9” pie dish. Tuck it in with your fingers, making sure it is smooth. Trim the excess, leaving about a 1 inch overhang. Fold the excess pie dough underneath, crimping the edges. Refrigerate the pie crust as you make the brownie filling.
Blind bake the crust. Preheat the oven to 350oF. . Line the chilled pie crust with parchment paper. Fill with pie weights, dried beans or rice. Make sure the weights are evenly distributed around the pie dish and filled to the top of the crust. . Bake until the edges of the crust are starting to brown, about 15 minutes. Remove pie from the oven and carefully lift the parchment paper/aluminum foil (with the weights) out of the pie. Prick holes all around the bottom crust with a fork. Return the pie crust to the oven. Bake until the bottom crust is beginning to brown and no longer looks raw, about 7 minutes longer. Remove from the oven and allow to cool on a wire cooling rack while you make the filling..
Make brownie filling. In a large saucepan, melt the butter. Remove from heat, and with a wooden spoon or spatula stir in sugar, and cocoa powder. Mixture will be quite thick.
Stir in the oil, eggs, and vanilla until smooth.
Stir in the flour just until combined. Stir in the chocolate chips. Pour brownie batter into prepared pie crust and smooth the top.
Bake. Place pie onto a cookie sheet. Cover the pie crust with a pie crust shield or strips of foil. Bake for 40-45 minutes, until the top is cracked and set. Do not overcook. Middle may still be slightly jiggly. It will firm up as it cools.