Line an 8 x 8-inch pan with parchment paper and set aside.
In a microwave safe bowl, add your peanut butter and microwave in 20-second spurts until melted. Add the vanilla frosting and melt for a further 20 seconds.
Transfer the fudge mixture into the lined pan and refrigerate for at least two hours, to firm up. Once firm, slice into pieces and sprinkle with flaky salt.
* Any frosting can be used. I used Betty Crocker Vanilla frosting, which is naturally vegan.TO STORE: Fudge should be stored in a sealable container in the refrigerator. It will keep well for up to 4 weeks. TO FREEZE: Place leftovers in a shallow container lined with parchment paper and store in the freezer for up to 6 months.