Spray a 9 x 13 glass baking pan with baking spray.

Melt the butter. Set 1/4 c of the melted butter aside.

In a large mixing bowl, mix together until fully blended 3/4 cup of the melted butter, graham cracker crumbs, 1 c of peanut butter and the powdered sugar. 

Evenly spread the mixture into the baking pan. Press it down so that it is evenly distributed.

Place the baking pan in the refrigerator to chill for 15 minutes. 

Add the chocolate chips, remaining butter and 4 tablespoons of peanut butter to a microwave safe bowl. 

Slowly melt the chocolate mixture in the microwave in 10 second intervals until it is smooth. Stir in-between intervals.

Remove the baking dish with the peanut butter mixture from the fridge.

Spread the chocolate mixture over the peanut butter mixture evenly.

Place the pan in the fridge and chill for at least one hour.

Remove and cut into small squares.

Serve chilled for better handling.