I just made 2 perfect batches of fudge to send to my son (Air Force) based somewhere in the Middle East. I do use whipping cream.
According to the recipe "A good basic chocolate fudge. The use of whipping cream or nondairy cream substitute makes stirring unnecessary. This makes a very creamy fudge."
3 cups sugar
2/3 cups cocoa (I use Hershey's Special Dark)
1/8 tsp salt
3 Tbl white Karo syrup
1 1/2 cups heavy cream (or non-dairy liquid cream substitute)
4 Tbl butter
1 tsp vanilla
Combine cocoa, sugar, salt, and heavy cream in a large saucepan. Bring to a rolling boil; then reduce heat to medium and cook to 234 degrees without stirring. Remove from heat and add butter and vanilla. Do not stir. Cool to lukewarm (about 110 degrees). Beat by hand or with mixer until fudge thickens and loses some of its gloss. Quickly spread fudge in lightly buttered 8-inch square pan. When cool, cut into squares. Makes about 64 pieces.
I don't use a candy thermometer. I use the soft ball test, using cold water and a drizzle of hot fudge. I don't beat it, I just stir the melted butter in and pour into the pan.