Mix together first 5 ingredients to combine.
Cook together over medium heat until liquid forms a nice smooth ball when dropped into ice water, mixture shouldn't be grainy. About 10 minutes.
Stir in marshmallow fluff until well combined. (Mixture will look a little pink at this point)
Then add peanut butter.
Stir until peanut butter dissolved and mixture turns light brown.
Pour into a 9x13 inch pan and let sit until set. (About an hour or two)
Cut into desired size blocks and serve.