In a medium-large bowl, combine butter, oil, and sugar and blend until creamy. Add vanilla and eggs and mix until combined. Set aside.
In a medium bowl, whisk together flour, baking powder, and salt. Once combined, add dry mixture to batter mixture and fold in chocolate chips. Place in a non-stick 9x9 pan and bake for 20-24 minutes or until wooden pick inserted in the center comes out clean and top is golden brown.