Stir together Cream and sugar in large heavy buttered pot. Place over medium heat and stir constantly just until it comes to a rolling boil. Once it starts to boil, DO NOT STIR, and put the lid on for ONE minute and then remove the lid.
Continue Cooking to a soft ball stage, and Do not Stir
Use your Candy Thermometer. I cook mine to about 230 degrees. Every thermometer is different, so test yours, or do the cold water test.
Take off the heat, and add 1 cup (2 sticks) of butter that you have cut up in chunks. Do not stir.
Add the vanilla. Do not stir.
Let sit in the hot candy mixture for ONE minute – WITHOUT STIRRING!
Now – Without scraping the pan, pour over 3 big (the 6.8 oz) symphony bars that you have broke up into a large bowl. Beat until very smooth with beaters.
Pour into a greased 9×13 pan. Put in the fridge until set up.
*I line my pan with parchment paper, that way you can lift the entire slab of fudge from the pan, and cut squares very easily.
Once cut, put in a container with a sealed lid, and keep refrigerated. YUM!