Mix graham cracker crumbs and powdered sugar well in a large bowl.
Add peanut butter and melted butter and mix well with clean hands.
Press into 9x13 baking dish working all the way to the sides and making the top flat.
Melt chocolate according to package directions in microwave. Pour over top of candy and spread evenly.
Allow to set in refrigerator for 2 hours or until chocolate has hardened.
Cut into squares. May be stored in refrigerator up to 2 weeks.
Notes
To make gluten-free peanut butter bars substitute gluten-free graham crackers. Crush in a plastic bag with a rolling pin or use a food processor.Make this recipe dairy-free by using a vegan butter or margarine instead of butter.