Line an 8 or 9-inch square baking dish with parchment paper. Set it aside.
In a large saucepan, heat granulated sugar, butter, salt and heavy cream until combined. Bring to a ROLLING boil and stir continuously for 4 minutes (set your timer)!
Remove from heat. Quickly whisk in white chocolate, marshmallow fluff, and peanut butter (I usually put these ingredients in my kitchen aid and whisk them for about 1-2 minutes). Pour fudge into prepared pan and allow to set for 3 hours, until hardened.
Remove from pan, remove lining. Cut into bite sized pieces. ENJOY.
Video
Notes
For a chocolate drizzle on top, melt 1/4 cup semi-sweet chocolate morsels. Drizzle over the set fudge and enjoy.
Store fudge in airtight container at room temperature or freeze for up to three months.