Butter or grease 2 6-inch square metal brownie pans (or 1 9-inch square pan)
Chop the nuts and set aside. Melt the butter.
Add the brownie mix to a medium-sized mixing bowl. Stir in the water, melted butter or oil and egg. Stir until well blended. Add the chopped nuts and chocolate chips and stir well to combine. The batter will be stiff and thick.
Divide the batter evenly between the two pans. Spread to smooth the tops.
Bake for 20 minutes. Check the pans and rotate. Bake for another 15 to 20 minutes. Do not overbake. Check frequently with a toothpick. The batter should just set up.
Cool on a rack for 5 minutes, then cool completely in the freezer. Cut each pan into 16 squares.