Mix water, sugars, and molasses in saucepan. Bring to boil.
2 c. brown sugar, 1 1/2 c. white sugar, 2/3 c. molasses, 2 c. water
Boil on medium heat for about 2 - 3 minutes.
Cool completely.
Add peanut butter and marshmallow cream and mix well, until smooth and creamy.
2 1/2 lb. peanut butter, 1 1/2 c. marshmallow cream
Serve on bread or buns. Or anything else you like peanut butter with.
Notes
You can use any kind of molasses or Karo for this recipe. It just depends on how well you like that robust molasses flavor. Blackstrap molasses has a very strong and distinct flavor that some people do not like. I would personally recommend using light-tasting molasses. And if you're not a molasses person, feel free to use light Karo. If you just want to try the recipe and don't want to make a lot, go ahead and halve the recipe.