Liberally butter the bottom and sides of an 8 x 8 or 9 x 9-inch pan. Alternatively, line with parchment or aluminum foil, leaving enough overhang to easily remove from the pan. Butter the foil.
In a heavy bottomed saucepan melt together the sweetened condensed milk and peanut butter. Cook over medium stirring constantly until bubbly. Allow to bubble for 2 minutes. Don't walk away.
Remove from the heat and add the peanut butter chips and vanilla. Stir until the chips have completely melted. If needed. move the pot back onto the stove over low heat while stirring constantly. Stir until smooth.
Mix in the chopped nutter butter cookies. Pour into the prepared pan. Spread evenly.
Chill while you prepare the topping.
In a microwave safe bowl, melt the milk chocolate chips and heavy cream. Heat in 20 second increments stopping to stir each time. Repeat until the chips have completely melted then add 1 tablespoon of light corn syrup. Mix well.
Pour the melted chocolate on top of the fudge and sprinkle with chopped peanuts.
Chill for at least 2 hours or until completely cooled and firm. Cut into desired size pieces.