This fondant recipe below is what I believe to be the best one out there, the rules are:
For enough fondant to feed a medium strength colony for 5 to 10 days, boil up:
to 238 degrees F.
Use a small pot, one that the thermometer can be submerged into the mixture for an accurate temperature reading. A small pot also makes it easier to scrape the remaining mixture out during the pour.
Remove it from the heat source and let it cool to around 140 degrees. This takes some time, and can be hastened by a short period of refrigeration if you are impatient. The latter can cause it to "gum up" around the edges of the cool pan requiring some heavier scraping/mixing to blend it until it "kicks over".
After the mixture has cooled to 150 degrees or so, squeeze in some honey (in place of 2 tablespoons light corn syrup, never use the dark colored corn syrup) if you have it, up to a quarter cup.
Start stirring until you see the mixture start to turn white (kick over) and can no longer see the bottom of the pan.
This is about the time you need to dump it out on the foil. If you dump it too early, as soon as it starts to turn opaque, it may never firm up upon cooling. If you stir too long, until it looks like cake frosting, you will need a hammer and chisel to get it out of the pan. The time to pour it is before you start to feel any resistance while you are stirring/whipping it.
OPTIONAL: You could also sprinkle some pollen substitute on the foil before you pour the fondant from the pan. Mega Bee is a very good pollen substitute.
To keep extra fondant moist for future use, or to re-introduce moisture into hard dry fondant, put it in a sealed contained with a piece of aluminum foil on top of it and a small piece of wet paper towel on top of the foil. Check back often and don’t let any water from the paper towel drip onto the fondant cake(s).
If you use honey in your fondant,
For thin fondant, move the pot as you pour, don’t just dump it out in a pile on the foil. If it’s still too thick, after it hardens you can smash it down by rocking a frying pan on it until it’s at the thickness you want. This action also re-hydrates the fondant and it will be sticky and difficult to handle. Scrape it off the bottom of the pan with a kitchen knife and put it on wax paper until you are ready to use it.
Light corn syrup can be used in place of honey but they really devour the honey fondant. I nursed 6; fall produced nucs through winter that ran out of stores/food in December using this recipe by placing fresh batches on top of the frames every 7 to 10 days or so. Use a shim on top of the box to elevate the inner cover so you don’t crush any bees when re-installing it, or turn the inner cover upside down if it’s recessed.
You can also use newspaper on top of the fondant and frames. Put another hive body on top to hold the newspaper in place, and then put the inner cover and outer cover back on top of the additional hive body. The bees can use fondant and generate heat immediately; they CAN NOT use a fresh, un-cured sugar syrup mixture from a feeder or from their honeycomb during the cold to generate heat. As well, they WILL NOT venture out of the cluster to feed on and take sugar syrup in temperatures below 50 degrees or so. This is why it's important to have your winter prep done well in advance of the approaching cold it can save you some emergency feeding labor.
If later during the cold months you pop the outer cover off and see a bunch of bees up top through the hole in the inner cover, chances are they are low on stores and will require emergency feeding. More on these very quick, cold, winter inspections later.