Brownies:

1 c. all-purpose flour
1/4 tsp. salt
1/4 tsp. baking soda
1 1/2 c. semi-sweet chocolate chips, divided
1/2 c. butter
3 oz. unsweetened chocolate, chopped
3 eggs
1-1/2 tsp. vanilla extract

Preheat oven to 350°F.

Line 9-inch square baking pan with foil so that it overhangs edges by 2-inches; coat with cooking spray. Combine flour, salt and soda. In pot, combine 1/2 cup chocolate chips, butter and unsweetened chocolate; over low heat, melt, stirring until smooth. Remove from heat; whisk in sugar until combined. Lightly beat eggs with vanilla; whisk into chocolate mixture until combined. Cool 5 minutes. Stir in remaining chocolate chips. Pour into pan.

Bake 25 minutes or until toothpick inserted into center comes out with moist crumbs clinging. Cool in pan on rack.

Frosting:

3/4 c. semi-sweet chocolate chips
2 tbsp. butter (at room temperature)
3/4 c. confectioners' sugar
1 tsp. vanilla extract
3 to 4 tbsp. milk

In microwave-safe bowl, melt chocolate on High, stirring once, until smooth, 30 to 40 seconds. Cool until lukewarm, 5 minutes. Stir in butter until smooth. Stir in half of sugar with vanilla extract; stir in milk, 1 tablespoon at a time. Stir in remaining sugar until smooth. Spread over brownies.