This recipe really requires two people to make as one needs to add the ingredients while the other is stirring. Completely butter a 9x13 pan or two square 9 inch pans if you want to add nuts to half the recipe and set aside.
Place both jars of marshmallow cream in hot water letting soak until just before adding. This makes the marshmallow cream much easier to remove from the jar. Break up the milk chocolate and open the bags of chips setting aside all ingredients. Open both jars of cream just minutes before the sugar mixture comes off the stove.
Combine butter, sugar and evaporated milk in a large heavy pot. Bring the ingredients to a boil for 5 1/2 minutes. Remove from heat placing on a hot pad.
Add alternating marshmallow cream and chocolate until completely mixed. This will require a pretty strong arm or alternating with the person who was adding the ingredients. Add in vanilla and optional nuts. Once it is completely combined pour in to the prepared pans and allow to fully cool before cutting. If you are adding nuts to half the recipe, pour half of the combined in to one pan, add nuts mixing completely and pour the rest in to another pan.