Pop the microwave popcorn.
Remove any unpopped kernels and place in large bowl.
In medium saucepan combine brown sugar and corn syrup. Bring to boil over medium high heat stirring frequently.
Remove from heat and whisk in peanut butter.
Pour over popcorn and stir until well coated.
Spread on cookie sheet lined with parchment paper then sprinkle with chopped peanuts. Allow to cool then enjoy!