Stir together melted butter and brown sugar.
Add eggs and vanilla and stir to combine. Add in baking powder and stir to combine
Gradually stir in flours.
Fold in chocolate chips.
Pour batter into greased 9x13" cake pan.
Bake at 350 degrees for 30-35 minutes.
Allow to cool completely before cutting. Enjoy!
Pre-heat oven to 350 degrees and grease 9x13" cake pan.