Use food processor to turn graham crackers into crumbs. Measure 1 1/2 cups fine crumbs. Add powdered sugar and blend with crumbs. Pour into mixing bowl. Add melted butter and peanut butter. Stir well.
Spoon peanut butter mixture into an ungreased 9 x 13 inch pan and pressed firmly into an even layer. (Use waxed paper to press) chill until cold, 45 minutes. Discard wax paper.
In 1 1/2-2 quart pan over low heat, melt chocolate chips. Stir until smooth. Spread chocolate evenly over chilled peanut butter layer. Let stand until chocolate firms slightly (15 minutes). Cut into 1-1 1/2 inch squares. 3 dozen.
