1Preheat oven to 350. Grease and flour a 9x9 baking pan.
Cream the sugar, eggs, and vanilla in a medium bowl until smooth. Add the cooled butter and mix until well blended. Measure the flour, salt and baking powder and sift directly into the batter. Gently mix the batter until well combined and no traces of flour remain. Stir in the butterscotch and chocolate chips.
Spread batter into prepared baking pan. Bake for 20-25 minutes, until a toothpick inserted in the center comes out clean or with crumbs. Cool for 1 hour. Cut into 12 or 16 squares.