Preheat the oven to 350℉.
Mix together the egg, butter, brown sugar, mashed banana and the vanilla extract. In a separate bowl, add the flour, salt, and baking powder.
Combine the dry and wet ingredients until just combined. Then, fold in the chocolate chips and walnuts.
Add the batter to a lined baking pan. Place in the oven and bake for 30-35 minutes or until the banana bread brownies have rise and a toothpick comes out the center clean.
Allow to cool for 20-25 minutes before cutting and serving, enjoy.