Melt cheese and butter together in a nonstick pan, stirring until smooth. Keep on low heat.
In a large bowl, sift/wisk powdered sugar and cocoa powder together. I start out with 4 pounds and add more if wanted (4 pounds will make a creamier fudge and 4 1/2-5 pounds will make a harder fudge).
Add vanilla to cheese mixture. With a heavy spoon, combine the cheese/butter mixture with the sugar and cocoa. Work quickly because it sets up fast. Add nuts etc. If you have a stiff candy, butter your hands and get in there and mix well until all the powdered sugar is incorporated.
Press mixture into 2 lightly sprayed or buttered pans. Sometimes I line the pans with nonstick foil and when set (usually overnight) I can lift it out and cut into squares.