Melt butter in a medium saucepan for the bottom layer.

Stir in graham cracker crumbs, brown sugar, and flour.

Press the mixture into an ungreased 9x9 inch pan.

Bake at 350°F (175°C) for 10 minutes.

For the second layer, stir sweetened condensed milk with coconut.

Spread the coconut mixture over the baked bottom layer.

Return to the oven and bake for another 10 minutes, or until lightly browned.

For the top layer, melt chocolate chips and peanut butter in a heavy saucepan over low heat, stirring frequently.

Spread the melted chocolate peanut butter mixture over the second layer.

Cool completely before cutting into squares.