Heat oven to 350F. Grease bottom only of 13 x 9 inch pan. In large bowl, combine brownie mix, water, egg and oil; beat 50 strokes by hand. Stir in 1/2 cup chocolate chips. Spread in greased pan and bake at 350F for 33-35 minutes; do not overbake. Cool completely. In large bowl, beat 1/2 cup butter, brown sugar and sugar until light and fluffy. Add milk and vanilla; blend well.
Add flour and mix well, then spread onto cooled brownies. In small bowl, melt 1 cup chocolate chips and 1 tbl butter on medium for 1-2 minutes or just until chocolate melts; stir until smooth. Carefully spoon glaze over filling and spread to cover. Sprinkle with chopped nuts, pressing down slightly. Cut into bars; store in fridge.