Preheat oven to 350 degrees. Line a 9x9 inch (or 8x8 inch) baking pan with foil and leave a 2-3 inch overhang on two sides. Spray with non-stick spray.
In a double boiler (or metal/heat proof bowl over a pot of boiling water) melt butterscotch chips and butter, stirring frequently.
Once melted, remove from heat and stir in brown sugar.
Add the eggs and vanilla, and whisk until just incorporated.
Stir in flour and baking powder.
Pour batter into the prepared pan. Sprinkle with butterscotch morsels.
Bake for 35 minutes or until a toothpick inserted into the center of the brownies comes out clean. (There can be a few crumbs on it.)
Let the brownies cool in the pan for 5-10 minutes. Lift brownies out of the pan by the foil overhangs and let them cool on a wire rack.