- Preheat oven to 350 degrees. Grease a 9 x 13 baking dish with pan spray.
- Combine cocoa powder, salt, baking powder, and flour together and set aside.
- Mix butter and sugar together in a mixing bowl until combined. Slowly add the eggs and vanilla, mix until combined. Add flour mixture all at once, mixing just until incorporated. Fold in chocolate chips.
- Pour into prepared pan and bake for about 30 minutes or until inserted toothpick comes out clean. Let cool completely.
- Tear brownie mixture into pieces and put into a mixing bowl. While the mixer is running, stream in the rum until brownies start clumping together. Continue adding rum to taste.
- Scoop with a spoon or ice cream scoop and roll into a ball with the palm of your hands. Place balls on parchment paper. Coat rum ball with powdered sugar and serve.