Stir chocolate and butter in heavy medium sized saucepan over low heat until melted and smooth. Cool to room temperature.
Combine flour, baking powder and salt in small bowl. Whisk together sugar, eggs and vanilla in medium bowl until mixture is very thick (about 3 minutes). Whisk in melted chocolate mixture, then flour mixture. Stir in white chocolate. Transfer to prepared pan.
Bake for approx 28 minutes or until tester inserted in center comes out with moist crumbs attached. Transfer pan to wire rack; cool completely.
Cut brownies into 16 squares. Serve brownies with starwberries.