Heat oven to 350°F. Spray a 9x9-inch baking pan with no-stick cooking spray.
Combine the graham cracker crumbs and butter in small bowl. Press into bottom of prepared pan. Top evenly with coconut. Pour sweetened condensed milk evenly over coconut layer.
Bake 20-25 or until lightly browned. Loosen from sides of pan while still warm. Melt chocolate chips with peanut butter in small microwave-safe bowl on high for 1 minute. Stir until smooth. Spread evenly over hot coconut layer. Cool 15 minutes on wire rack. Refrigerate 45 minutes or until chocolate is set. Cut into bars.
The original recipe called to put these in a 9x13 pan which I tried, but I didn't think there was even close to enough graham cracker crumbs to cover the bottom of the pan, so I opted for a smaller pan and I am so glad I did.