Melt butter over medium heat. Add sugar and evaporated milk and slowly turn up the heat so mixture comes to slow boil.
Let mixture come to soft ball stage (234-236°). Lightly stir and when making candy be sure to wipe down the sugar crystals on the side of the pan with water and a pastry brush. Take a bit of the hot mixture and throw in glass of water. If it goes into a ball its ready to remove from stove.
Remove from burner and add in the peanut butter, marshmallow creme, and vanilla.
Pour immediately into a greased 8×8 square pan. Let cool for several hours before cutting into 1" pieces.
Store in sealed container in a cool location such as garage or fridge.
