Make brownies as directed using oil, egg substitute, and water. Bake as directed in a 13 by 9 pan.
After allowing brownies to fully cool (about 1 hour), mix peanut butter and frosting together using an electric mixer. Spread on brownies. (Yes, it is kind of thick.).
Melt chocolate and butter in a microwave safe dish on high approximately 1 to 2 minutes (stirring every 30 seconds). Allow mixture to cool about 10 minutes before spreading over frosting. Allow to set in refridgerator 30 minutes before cutting into brownies. These are rich, so cut them fairly small (then eat two!).