Spray a 9x13-inch glass baking dish with non-stick spray.
Place 2 whole graham cracker sheets in a ziploc bag and crush into crumbs with meat mallet or the bottom of a glass. Set aside.
Mix peanut butter, butter, vanilla, and salt. Slowly add in powdered sugar a little at a time.
In microwave safe bowl heat chocolate chips with shortening. Heat for 30 seconds at a time, stirring between, until smooth. Be careful not to overcook.
Lay first layer of graham crackers (6 whole sheets) in sprayed baking dish.
Pour about ⅓ of the chocolate into a thin layer over the graham crackers.
Using your hands, take fistfuls of the peanut butter mixture and flatten. Lay on top of the chocolate layer. Cover as best you can without breaking the graham crackers below. You will use all of the peanut butter mixture.
Layer another ⅓ of chocolate on top of peanut butter and then layer again with graham crackers (6 whole sheets) and pour remaining chocolate on top.
Sprinkle crushed graham cracker crumbs on top.
Let cool in refrigerator for at least 1 hour. Cut into squares, big or small.