For an extra layer of flavor, consider toasting the flaked coconut lightly before adding it to the filling. This will enhance its nutty flavor and add a pleasant textural element. To prevent the chocolate chips from burning in the microwave, be sure to stir them frequently during the melting process. If you prefer a thicker crust, you can use 1.5 times the cake mix and butter. Store leftover cookie bars in an airtight container in the refrigerator to maintain their texture and freshness.