Warning: this recipe requires constant supervision. The caramel mixture can get quite hot and can burn easily.
First, lightly grease a 8x8 inch pan and line the pan with parchment paper. Set aside.
Over medium low heat, add the corn syrup to a heavy bottomed sauce pan. Bring to a low boil -
a low boil means you should see small bubbles forming. As soon as you see that, add the peanut butter and vanilla. Stir into the hot corn syrup. Allow to cook for two minutes before adding the chocolate chips.
Stir the chocolate chips into the mixture until melted. Allow this mixture to cook for 2-4 minutes, stirring constantly.
Remove from heat and add two cups of the peanuts.
Pour the entire mixture into the prepared 8x8 pan. Use an off-set spatula to press the mixture into the pan and into the corners.
Top with the remaining half cup of peanuts. Lightly press the peanuts into the fudge mixture.
Allow to cool for 4 hours at room temperature. Cut into squares.
To store, place in food-safe container and separate layers with parchment paper. Can be frozen for up to 6 weeks.