I made these for cooking class one day and my teacher thought they were the best she ever had! made them again for thanksgiving and for friends and they could not just get enough!! they just kept wanting more and I'm pretty sure you will too when you make these.
Preheat oven to 350 degrees Fahrenheit. Lightly grease pan.
Place chocolates,both milk chocolate and semisweet into microwave, and butter safe bowls. Microwave for 2 mins or until butter AND chocolates are melted. Stir until mixture is smooth.
Combine flour, salt,and baking powder in small bowl. Beat sugar, eggs, and vanilla into large bowl until thickened. Beat in melted chocolate, Pour in butterscotch chips. Add flour mixture and beat until blended. Add sour cream and blend until mixture is even.
Pour and spread mixture into the pan. bake 25 to 30 mins or until center is firm to touch. Cool brownies completely. Sprinkle with powdered sugar and ENJOY!