Food Guys Greg Patent and Jon Jackson explore candy-making, caramelization, and the chemistry of cooking with sugar.
But let's cut to the chase. To make fudge, combine cocoa, milk, butter and sugar and cook the mixture until it reaches the recommended temperature. Cool it quickly to another pre-determined temperature, then mix it to just the right thickness, pour it into a prepared pan, and let it sit for several hours. "Foolproof" fudge recipes simplify this process by incorporating marshmellows, but as Greg points out, "That's kind of cheating."
You'll need to pay attention to your kitchen's elevation. If the recipe assumes that you're at sea level and instructs you to boil the ingredients to 234 degrees F, reduce that temperature by two degrees F for every 1,000 feet above sea level at your location. This is when a candy thermometer becomes essential.
Greg Patent makes caramel sauce without cream or butter by putting white sugar into a skillet and cooking it on medium heat for ten minutes, shaking the pan occasionally, then stirring it up. He continues cooking, first until the sugar has become a free-flowing liquid, then till it's dark and flavorful.