In large mixing bowl, with an electric mixer at medium speed, cream together the butter and both sugars until light and fluffy. Beat in the egg and vanilla. Gently stir in flour mixture until just combined. Fold in the white chocolate and macadamia nuts. Bake for 9 to 12 minutes or until lightly golden, turning cookie sheet around after 5 minutes to ensure even browning.
Transfer cookies to a wire rack and cool completely.
Store in airtight container. Makes about 5 dozen cookies. Continue stirring until just thickened and immediately pour through a strainer to stop cooking. Do not let it boil, or it will curdle. Stir in the remaining ingredients while still warm, then allow to cool thoroughly.