How to Make It
Preheat oven to 350°F. Microwave chopped chocolate in a microwavable bowl at MEDIUM 2 minutes or until melted, stirring at 30 second intervals. Stir until smooth.
Beat together butter, granulated sugar, and brown sugar with a heavy-duty stand mixer at medium speed until light and fluffy. Add eggs, 1 at a time, beating just until blended after each addition. Add melted chocolate, beating just until blended.
Stir together flour and salt in a small bowl. With mixer running on low speed, add flour mixture to butter mixture; beat just until blended. Stir in chocolate morsels and vanilla. Spread batter into a greased and floured 13- x 9-inch baking pan. Bake in preheated oven until center is set, 30 to 35 minutes. Cool completely on wire rack. Cut into squares; dust with powdered sugar.