Spray a 9"x13" pan with nonstick cooking spray. Line with one layer of club crackers. Set aside.
In a medium saucepan on the stove, mix butter, milk, sugars and graham crackers.
Bring to a boil, adjust heat to medium low and stir constantly for 4 minutes.
Pour half of the filling over the club crackers and spread evenly.
Top with another layer of club crackers.
Add the rest of the filling on top of the club crackers. Spread evenly.
Top with a third layer of club crackers and set aside.
In a microwaveable-safe bowl, melt the chips and peanut butter, stirring until smooth.
Spread over top of club crackers.
Place in refrigerator to cool for at least 2 hours.
Cut into bars and serve.