While the crust is baking, start the brownie batter. In a mixing bowl, sift the flour, cocoa powder, cornstarch, and salt. Set aside.
1/2 cup All-purpose flour, 1/2 cup Unsweetened cocoa powder, 1/2 TBSP Cornstarch, 1/2 tsp Salt
Using a mixer, beat the sugar and eggs on high speed for 2 minutes. Add the melted butter, oil, and vanilla. Mix on low speed until combined.
1 cup White granulated sugar, 2 Large eggs, 1/4 cup Unsalted butter, 1 tsp Pure vanilla extract , 1/4 cup Oil
Add in the dry ingredients. Mix on low speed until almost combined. Take off the mixer and mix with a baking rubber spatula.
Pour the batter on top of the baked crusted and spread evenly.
Bake for 27-29 minutes. Bake until a toothpick inserted comes out with moist crumbs. Let the pie sit on a wire rack and cool completely.