Preheat oven to 350 degrees F and line an 8x8 or 9x9 inch baking pan with parchment paper. (spray or butter pan before putting parchment paper in to help it stick to the pan).
In a bowl whisk together melted butter, brown sugar, egg and vanilla.
Next whisk in flour, salt and baking powder.
Lastly, mix in butterscotch chips then pour into prepared baking pan and spread evenly. If the dough is too sticky to to spread, butter fingers to help spread out the dough.
Bake for 25-28 minutes. I suggest under-baking slightly to achieve a chewy blondie. Let cool completely before cutting.