Here’s my Never Fail Chocolate Fudge recipe. This recipe is adapted from a 1981 edition of Favorite Brand Name Recipe Cookbook. My notes are in parentheses.
2 1/2 cups sugar (I reduce it to 2 1/4 cups)
1/2 stick butter (I use unsalted)
3/4 cup evaporated milk (I use fat free)
1 7 1/2 ounce jar of marshmallow fluff
3/4 tsp salt
3/4 tsp vanilla extract
12 oz semisweet chocolate (quality matters--I use Ghiardelli)
1/2 cup chopped nuts, if desired

Combine first five ingredients. Stir over low heat until blended. Bring to a boil over moderate heat being careful not to mistake air bubbles for boiling. (VERY IMPORTANT) Boil slowly, stirring constantly for a full 5 minutes. (Also very important!).
Remove from heat and stir in vanilla and chocolate until chocolate is melted. Stir in nuts if needed. Turn into a buttered (I use butter flavored cooking spray) 9 x 9 inch pan and cool completely.(This makes about 2 pounds of smooth, rich fudge.)