Preheat oven to 350°F.
Lightly grease an 8x12-inch baking pan with cooking oil spray or regular canola oil.
Mix melted butter, oil and both sugars together in a bowl. Whisk well to combine.
Add the eggs and vanilla; beat until lighter in color.
Sift in flour, cocoa powder and salt. Gently fold the dry ingredients into the wet ingredients until they combine.(do not over beat. This can affect the texture of the brownies). Fold in 2/4 of the chocolate chips.
Pour the batter into prepared pan. Add the remaining chocolate chips on top of the batter.
Bake for 25-30 minutes for fudgier brownies or 35-40 for more done and firm texture brownies.
Remove and allow to cool to room temperature before slicing into the brownies. About 16 slices.
Enjoy!