Preheat oven to 350 degrees F. Line a 9x13-inch baking dish with parchment paper or grease with non-stick spray. Set aside.
Mix melted butter, oil and both sugars together in a large bowl. Add the eggs and vanilla extract. Mix until combined. *(You can mix this all by hand with a spatula or use an electric hand mixer.)
In a separate large bowl, add the flour, cocoa powder, and salt. Using a whisk, stir and sift to combine these dry ingredients together. Gradually add dry mixture into the wet mixture just until combined. Don’t over-mix. Fold in half of the chocolate chunks. Batter will be thick.
Pour batter into the prepared baking dish. Spread out evenly. Top batter evenly with the remaining chocolate chunks/chips.
*For fudgy brownies bake for 22 to 25 minutes.*For more set brownies bake for 30 to 35 minutes. Carefully remove brownies from oven. Allow to cool for at least 1 hour before cutting. Serve and enjoy!