Preheat oven to 350 degrees Fahrenheit. Lightly grease a 8x12 inch baking pan and line with parchment paper. Set aside.

In a large bowl combine melted butter, vegetable oil and both sugars. Whisk well and then add in eggs and vanilla. Beat until lightened in colour.

Sift in salt, flour and cocoa powder. Gently stir to combine. Add in ¾ amount of the chocolate chips, reserving ¼ for later use. Stir to combine.

Pour batter into prepared pan and top with remaining chocolate chips. Bake for 25-30 minutes or until brownies look "set." Brownies will cook further and "set" as they sit at room temperature.

Let brownies cool for 15 minutes before cutting into them. The brownies can be kept stored at room temperature for 3 days or in the refrigerator for 5 days. They can also be frozen for up to 3 months. Thaw in the refrigerator overnight and then bring to room temperature. They can also be reheated in the microwave.