Cover an 8 x 8 baking dish with foil leaving the foil edges hanging over the pan to use to lift the fudge out of the pan after the fudge has set. Set aside.

In a medium sauce pan, bring half and half, butter, white sugar, and brown sugar to a boil. Stir constantly.

When mixture reaches a boil, boil for 7 minutes to dissolve sugars.

After the 7 minutes, remove from the heat and stir in marshmallows, peanut butter, and vanilla until smooth.

Spread into the prepared 8 x 8 pan.

Refrigerate for at least 3 hours to set.

Lift fudge out of the pan, cut into squares. Serve and enjoy or store in an airtight container until ready to eat.