marbeled peanut butter fudge

4 C sugar
1 can evaporated milk
1 C butter (i only use butter, but margarine can be used)
1 (7 oz) jar marshmallow fluff
3 C chocolate chips
1 Tbl vanilla
1 C peanut butter (i use super chunky)

1. In a heavy saucepan, boil the first three ingredients for 8 minutes, stirring constantly.
2. Add the next three ingredients, stirring well after each addition. Remove from heat (keep stirring frequently).
3. Pour half of the chocolate fudge into a buttered 9x13x2-inch pan.
4. Dollop peanut butter around pan, and pour the rest of the chocolate fudge on top. Swirl with a knife or offset spatula.
5. (Optional) Place a sheet of wax paper on top of the surface (to keep it from drying too much while it cools) pressing it all the way into the corners of the dish.
6. Chill until set. Depending on the humidity, it could take a couple of days. Slice into bite-size squares. This is a very rich fudge. Makes about 5 pounds.