In a large pan, melt the butter and sugar together, add the rosemary, salt and garlic powder until blended and bubbling, throw in the walnuts and stir gently until they are coated with the mixture.
Place coated nuts into a large shallow pan and put into your smoker (on the smoke setting) for 1 hour.
Allow to cool before serving ... store in an airtight container for up to 1 month.