1. Pop corn and mix with nuts in a large bowl or roaster pan.
2. Combine sugar, butter, and syrup in a 2-quart saucepan. Bring to a boil over medium heat, stirring constantly.
3. Continue boiling for 10 to 15 minutes. Syrup will turn a light caramel color.
4. Remove from heat and stir in vanilla.
5. Pour over popcorn/nut mixture and stir to mix well.
6. When cool, break into chunks.