Hi Penguin,
Ok, here it is.
boil 1 cup water in a heavy pot
stir in 3 cups sugar and stir till dissolved
add a small pinch cream of tartar or 1 tb corn syrup and stir (watch it doesn;t make it boil over)
boil, covered, so the steam washes down the sides of the pot - or you can wash the crystals of sugar off the sides with a very wet brush
cook uncovered, and don;t stir any more at all (you may introduce crystals) until 238-249 degrees (soft ball)
Pour directly onto a marble slab and let it cool. Start scraping with a bench scraper, a flat spatula or egg turner or other flat scraping thing (big flat knife) - scrape it up towards the center, continuing on and on until it starts to turn from transparent to opaque. (What's happening here, i think, is that the molecules of sugar in the water have become amorphous and lost their specific pattern of being lined up in squares, but when it begins to dry, some crystals form on the marble, but instead of being large ones like in the original sugar, they're very tiny. The presence of patterns of crystals in the syrup begins to make the other molecules align with them - like when you put marbles in a dish, and they end up making triangular formations. Eventually it will be completely white and kind of crumbly. Then begin kneading it, until it's all smooth.
Wrap very well in plastic, and let it ripen half a day or more.
You roll it out like dough on waxed paper or on a greased surface, just like pie dough. it lifts up and can be carried around the rolling pin to the cake. (If you use it on a cake you should put a layer of frosting of some kind underneath or a layer of marzapan, brushed with jam, to make it stick)
You can also heat the fondant in a double boiler, with about two or three tbsp of liquid- water, vanilla, coffee, liqueur, and then pour it over the cake.
It gives a nice chewy consistency that is a great foil to certain cakes, and is also what they put on napoleons and, mixed with chocolate, what frosts eclairs.