Line 9-inch square pan with foil, extending foil over edges of pan; butter foil.

Cover bottom of prepared pan with chocolate chips.

Combine cashews, macadamia nuts, butter, sugar and corn syrup in large heavy skillet; cook over low heat, stirring constantly, until butter is melted and sugar is dissolved.

Increase heat to medium; cook, stirring constantly, until mixture begins to cling together and turns golden brown.

Pour mixture over chocolate chips in pan, spreading evenly.

Cool.

Refrigerate until chocolate is firm.

Remove from pan; peel off foil.

Break into pieces.

Store tightly covered in cool, dry place.