Toss together popped popcorn and cashews in a large roaster pan; keep warm in a 250-degree oven.
In a heavy 11/2-quart saucepan, combine sugar, honey and corn syrup. Bring mixture to a rapid boil over medium heat, stirring constantly; boil for 2 minutes. Remove from heat; stir in peanut butter and vanilla. Immediately pour over popcorn mixture, stirring to coat thoroughly. Spread on greased aluminum foil to cool. Break into bite-size pieces.