In a small bowl, combine graham cracker crumbs and butter; mix well.
Butter a 13x9 inch baking pan inside or use cooking spray.
Press crumb mixture firmly on the bottom of the baking pan.
Top evenly with coconut then pour sweetened condensed milk evenly over coconut layer.
Bake for 25 minutes or until lightly brown.
Meanwhile, in a small saucepan, over low heat, melt chocolate chips and peanut butter together.
Spread evenly over hot coconut layer. Cool for 30 minutes.
Cut into bars. Store loosely covered at room temperature.
Notes
Some people who made this recipe said that the crust might be too thin. If you prefer it thicker, just double the amount of graham crackers and butter.
Make sure you butter the pan all over inside. My experience is that the bars tend to stick all around the edges if you skip this step. You could also use parchment paper instead of butter, if you prefer.
If you do not like peanut butter, you can use some other types of nut butter, like almond for example.
This recipe has a thick layer of chocolate and peanut butter on top, some people might like it a little bit thinner. If that, you can use only 1 ½ cups of chocolate chips instead of 2 cups as the recipe requires.