Preheat the oven to 350 degrees. Line a 11X9" baking pan with parchment paper, leaving about 1 inch hanging on the sides.
In a heatproof bow, melt the butter and the chocolate, either in the microwave of in a bowl set on top of a pan with simmering water. (if using the microwave, stir the chocolate every 30 seconds to prevent burning it). Stir until smooth.
While the chocolate is melting, in a mixing bowl add the eggs, vanilla and sugars.
With the paddle attachment on, beat on medium low speed until foamy and pale in color.
Stir the melted chocolate mixture into the egg mixture.
Gently, fold in the flour without and give the batter a light beat.
With a spatula, fold in the butterscotch chips.
Spread the brownie batter evenly in the prepared pan.
Bake for 33-35 minutes, until a toothpick comes out clean. Don’t over bake!
Let the brownies cool completely before cutting into bars.