Mrs. J's Fudge

I got this recipe from my HS Chemistry teacher. It is THE best fudge I've ever tasted. We made it to sell for fundraisers. I haven't made it since because it is probably one of the most fattening things you can eat...but I'm sure I will want to make fudge again someday.

2 sticks margarine
4 1/2 cups sugar
1 can evaporated milk
10 oz. marshmallow cream
3 cups chocolate chips (I prefer peanut butter chips for peanut butter fudge)

melt butter on med heat
add sugar and milk, raise heat to high
bring to roaring boil
start timer for 9 minutes
reduce to medium heat
stir constantly till timer goes off
remove from heat, add chips
let melt partially, add marshmallow cream
stir till dissolved
pour into greased 9 x 13 pan
refrigerate

If you cook it too long it will be hard and dry, not long enough and it will be soft and mushy. its kinda tough to get it just right