Melt butter in pot and coat inside edges
Add Sugar, Milk, Syrup and Vinegar.
Bring to Boil and stir till 245°F
Fudge should form ball into ball when dropped from spoon into cold water, then rolled between fingers.
Remove from Heat and do not scrape sides after removal from heat.
Add Peanut Butter, Marshmallow Cream and Vanilla.
Stir till smooth
Pour into greased 7" x 9" pan