Preheat the oven to 350F and line a 9x13 pan with parchment paper, aluminum foil, or spray with non stick cooking spray.PRO TIP: Lining the 9x13 pan will let you lift the slab of brownies out without digging brownies out with a spatula! Measure the flour, cocoa powder, baking powder, and salt into a bowl and whisk them together to blend and break up any cocoa powder lumps.
1 cup flour, ¾ cup cocoa powder, ½ teaspoon baking powder, 1 teaspoon salt
In a large mixing bowl, mix the softened butter, oil, sugar, and vanilla until just blended. Don't over mix!
½ cup butter, ½ cup vegetable oil, 2 cup sugar, 2 teaspoon vanilla extract
Add the eggs, one at a time and mix until just blended, again don't over mix and incorporate air into the mixture.
4 large eggs
Add the whisked flour and cocoa powder mixture in two or three increments mixing until the flour is just blended in completely. Don't over mix.
Pour brownie batter into the prepared 9x13 baking pan and bake for 30 - 35 minutes. Check at 30 with a toothpick in the center of the brownies. If it comes out clean, remove immediately. The brownies will continue to cook as they cool.
Set brownies on a cooling rack to cool, and mix up the cream cheese frosting!