Preheat oven to 325° and spread the cashews out on a large sheet pan (or two). Toast cashews in the oven until warm, about 10 minutes.
While toasting, melt your butter and add the rosemary, cayenne, salt and brown sugar. Remove hot cashews from oven and carefully pour into a large bowl. Pour the slurry of butter, rosemary, etc over the top and gently toss them in the spiced butter. Return to pan(s) and bake until warm and a bit dry and brown, about 3-5 minutes more.
I buy the large tub of salted cashews from Costco (2.5 lbs) and bake on two large cookie sheets, adjust the slurry recipe accordingly for the number of lbs you are roasting.
Allow nuts to cool for 5 minutes, then using a spatula stir them around, scraping up the good stuff and allow them to cool completely. Once cooled, may be frozen.
To warm, place desired amount of cashews to small cookie sheet in a preheated 150-200° oven, heat until warmed through, about 4-6 minutes. Or place desired amount in a microwave safe bowl and heat for 30 seconds at a time, don't overheat they will get rubbery. May be served warm or room temp.
Notes
For a hostess gift wrap in cello bags and tie with a string or place amount in jelly jar, see post for details.