Grease an 8 x 8 x 2-inch baking pan; set aside. In a medium saucepan, combine 1/3 cup butter, the granulated sugar, and water. Cook and stir over medium heat just until boiling. Remove from heat. Add the 1 cup of chocolate pieces; stir until chocolate is melted. Stir in eggs and vanilla, beating lightly with a spoon until just combined. Stir in flour, baking soda, and salt. Stir in pecans. Spread batter into prepared pan.
Bake in a 350 degree oven about 20 minutes or until edges are set and begin to pull away from sides of pan.
Using fork, prick the warm brownies several times. Drizzle bourbon evenly over brownies; cool in pan on a wire rack.
For frosting, in a small mixing bowl beat the 3 tablespoons butter with an electric mixer on medium to high speed for 30 seconds. Gradually add powdered sugar, beating well. Slowly beat in 2 tablespoons of the milk and vanilla. If necessary, beat in remaining milk to reach spreading consistency. Spread over brownies; drizzle melted chocolate over brownies.