Put the sugar, cocoa, and salt into a *big* saucepan. Fudge will expand to up to four times its volume while cooking. Mix.
Add cream a little at a time, mixing as you go, until all cream is added. Mix well.
Add milk, syrup or honey, and butter. Cook mixture on high, stirring constantly, until it begins to boil.
Reduce heat until the mixture is merely bubbling. If too hot, mixture will expand and boil over. If too cool, mixture will not bubble. A slow, rolling boil is optimal. Cooking time begins at this stage.
Line a 9x13 or 8x11 pan with tin foil, being careful not to puncture the foil. Make sure foil is smooth in pan.
After mixture has cooked for about 15 minutes, begin testing it every five minutes. If recipe is doubled, double cooking time as well! Total cooking time is about 30-45 minutes for single batch.
To test: Fill a tall clear glass with cold tap water. Drop a few drops of the mixture into the glass from just above the water surface. As the mixture cooks, the drops will begin to appear less flattened on the bottom of the cup.
When the drop's height is at least half its width, the fudge is done. Make sure you rinse and re-fill the glass before each test.
Remove from heat, add vanilla, and mix. Allow mixture to cool for a while (NOT until it hardens, just until it isn't so hot that your foil-lined pan melts. You'll know because it will start to stiffen and form a skin on the top which cracks when you touch it. If in doubt, don't wait too long!)
Stir mixture violently until it loses its shiny appearance and begins to stiffen. Pour mixture into foil-lined pan and cool in refrigerator overnight.
Remove fudge from pan by lifting foil. If fudge hasn't hardened, Return to pan and cook some more.
Place fudge foil up on a cutting board and peel foil off. Cut with large knife by pressing knife into fudge (slicing doesn't work).
Options: Instead of cocoa, add 1/2 cup peanut butter *after* cooking
Add 1/2 cup walnuts after cooking. Omit cocoa and cook longer for caramel flavor (will harden quickly - pour into foil right after removing heat)
