Add the sugar, ¾ cup butter and evaporated milk to a medium saucepan and apply medium-high heat.
3 Cups Granulated Sugar, ¾ Cup Unsalted Butter, 1 (5 Ounce) Can Evaporated Milk
Keep stirring until all is melted together, then bring to a boil.
Allow to keep boiling on a low roll (without stirring) for 5 minutes. You're looking for soft ball stage (235°F on a candy thermometer).
Add the marshmallow creme, chocolate, salt and vanilla and turn off the heat.
1 (17 Ounce) Jar Marshmallow Creme, 1 (12 Ounce) Bar Semi-sweet Chocolate, 1 teaspoon Vanilla Extract, ½ teaspoon Salt
Keep stirring, the sugar mixture is plenty hot enough to melt all the chocolate and marshmallow creme.
Fold in the chopped walnuts, if you're adding.
1 Cup Walnuts
Pour the fudge mixture into a 9x9" square baking pan, lined with parchment paper.
Shake it out so that it's even, then set down to cool for 3 hours.
After 3 hours, remove from the pan using the parchment paper and cut the Amish fudge into 1" cubes of deliciousness.
Notes
Adding nuts is completely optional, walnuts or pecans are common.There was a stage where a lot of Amish recipes used Margarine instead of butter - a lot of the Amish community do still use margarine - so if you're looking for a more authentic fudge - swap out the butter for margarine. I just happen to think it tastes better with butter.