Lightly grease an 8" square pan and then line with parchment paper. Set aside.
Combine melted butter, oil, and sugar together in a medium bowl and whisk for about a minute. This will give the brownies a nice crust.
Add the eggs and vanilla and whisk for another minute.
Add the flour, cocoa powder, and salt, stirring just until the ingredients are combined. Do not over beat or you will end up with cake brownies.
Pour the batter into the pan and bake for 20-25 minutes. If you test for doneness with a toothpick the pick will come out with thick fudge crumbs. The brownies will continue to bake while in the pan cooling.