Disclaimer: I always cook by feel, rather than exact quantities. Fondant especially cannot be measured accurately. Hence, I cannot give you exact amounts, but I can give you a rough ratio from which to go by.
Start by getting everything ready: Fondant dries in the air quickly, so the last thing you need is to be scrambling last minute for utensils or ingredients.
The ingredients are pretty basic.
What You Need:
- Marshmallows (Most people use mini, but I cannot find white mini marshmallows for love nor money. Big ones work fine)
- PURE icing sugar (I cannot stress enough that this needs to be pure. To test for pure icing sugar, stir teaspoon of icing sugar into cold water and stir. Leave to sit for a few minutes; if water clears, icing sugar is pure. If a layer of starch settles at the bottom, it is not pure.)
- Cornflour (for dusting work surface/hands -- DO NOT use icing sugar to dust work surface)
If you are flavouring the fondant, get you colours and flavours ready.
You also need:
A microwave safe bowl
A wooden spoon
Lets get started.
Now, for quantities. It is roughly a ratio of 1 cup marshmallows : 2 cups icing sugar. IMPORTANT: When measuring, be sure to squish down the marshmallows, otherwise you will be under measuring.
I use the jumbo pack of Pascals marshmallows. A mix of pink and white, cause I can't find pure white anywhere. Pre-coloured/flavoured marshmallows are great if you happen to want that colour of fondant. Otherwise, they're just a pain. I separate the colours and leave the pink ones for other desserts or dunking in hot chocolates.
Conveniently, the amount of marshmallows in this packet equates to exactly 2 cups. Even more convenient is that it needs almost exactly 1 packet of CSR pure icing sugar (500g net), which is about 4 cups. So all you need (this will differ in other countries) is one pack of marshmallows and one pack of icing sugar to make one batch of fondant. Easy to remember, huh? You can half/double this quantity as per your requirements.
Okay, enough blabbing and more fondant...ing?
Put the 2 cups of marshmallows in a microwave safe bowl with 1 tablespoon of tepid water. Zap it at 30 second intervals, stirring in between, until mixture becomes soupy (see above picture). And I mean soupy. Not just melted, it has to be literally runny.
If you want to flavour/colour your fondant, now is when you can do it. But I always need white and several smaller lots of random colours, so I always colour after the jump.
Now sift in your icing sugar a cup at a time and combine with your wooden spoon. Do not use your hands. You will burn the living crap out of them. I have lost count of the amount of times I have read complaints about burns from making marshmallow fondant. Just don't do it.
Sift in the icing sugar a cup at a time: stir in the icing sugar with your spoon until you can't any more. It will become really tough and physical toward the end. Use your spoon to knead it when this becomes the case. You will get tired arms, but believe me, it is better than finding your arms have been swallowed by sticky fondant. I can knead it to near completion with a spoon. There are no photos of this point, because my hands were covered in icing sugar and I'd like my camera to stay not wrecked.
Once you cannot knead it any longer, get your fingers into it. By this stage you should not have used all 4 cups of icing sugar: you probably would not physically have been able to work the rest of it in with just the spoon. You will probably have worked in about 3 to 3 1/2 cups of icing sugar thus far. The fondant should only be slightly sticky, but in the case it is more than this, have your excess icing sugar at the ready in case your hand gets glomped by fondant anyway. To avoid mess, knead it one handed inside the bowl: this frees up one hand should a moar-sugar-rescue-mission be needed. If you've worked it enough with the spoon, it should be perfect to start kneading by hand. By the end of this step, it will look like above.
Turn it and the excess icing sugar that will probably still be in the bowl onto your work bench. Now we're going to work in the remaining icing sugar. Spread it little by little on the work bench like this:
Put your ball of fondant on top and gradually knead the icing sugar in until it is elastic, smooth and no longer sticky, keeping your hands well dusted as you go.
IMPORTANT: Do not work in the icing sugar until it is completely dry. It will crack and you'll never get it to smoothly cover you cake. Your fondant will remain very very slightly sticky. This is why you need to dust your work surface with cornflour (I believe this is called cornstarch in other countries). It will stop your fondant from sticking to everything. If you dust with icing sugar, one of two things will happen: you will work in too much icing sugar and your fondant will become dry and cracked; or it will become sticky and stick to your work bench/tools/hands.
This is why it is important to do it by feel rather than by measurement. The amount of sugar needed will depend on a plethora of things, even your climate. The last time I did it, I used the entire bag of icing sugar. This time, I had a handful left over. If you don't know what fondant should feel like, go buy some pre-made stuff and have a play before attempting to do your own. You'll very quickly pick up the gist of it.
By the end of this, you should have a lump of fondant that looks something like this:
Now you are ready to roll and colour and mould to your heart's content.
If colouring, ALWAYS used gel/powder colours. NEVER use the liquid stuff. It will wreck your fondant. Trust me, I started off using liquid fondant and dusting with icing sugar (more for lack of having the right stuff than anything) under the notion of "how much worse could it be?" The answer is VERY BAD. As long as you have gel colours and dust with cornflour, you will avoid the two biggest fondant disasters most people encounter. MMF is very forgiving and will roll fairly thin without the constant need for re-dusting that usual fondant does, but still be wary of it: shift the fondant and re-dust your work surface as appropriate. Lastly, always remember to cover your excess fondant with plastic to protect it from drying out as you work.
Anything unclear? Ask away and I will get back to you ASAP.
I hope this helped at least one person. :)