Line a 9x13 inch baking dish with aluminum foil and grease with butter or margarine.

Place a single layer of whole trefoils across the bottom of the prepared dish.

In a saucepan, combine the butter and brown sugar and bring to a boil over medium heat, stirring. Continue to boil for 3 minutes.

Slowly pour the syrup over the trefoils and spread gently to coat completely. Bake at 350 for 7 minutes or until bubbly.

Remove from oven and sprinkle with chocolate chips. When the chips have melted, spread the chocolate evenly over the top.

Sprinkle with nuts. Refrigerate until complete cool and set, then break into pieces.