AHi all. I tried to make marshmellow fondant last night. It was a disaster. I followed recipe, did as per instruction but my fondant turned out like a messy sticky pudding instead of like a dough. Help! Where did I go wrong? I used marshmellow, icing sugar, water.

Maybe you just didn't use enough powdered sugar?

It firms up with more sugar.

Is it possible you didn't add enough icing sugar?  When I first made MMF I threw the whole batch out because it was a sticky mess, but next time I tried again and just kept adding more and more icing sugar until eventually it stops sticking (but is still pretty soft).  At this point I wrap it and leave for a couple of days and it comes out perfect.

I don't even measure out my icing sugar anymore I just keep adding more and more until it loses its stickyness and comes together.

HTH

Same here. Just keep adding more confectioners sugar. And when you say you added water, how much - all you need is a couple tablespoons full or a quick splash from the water faucet (very quick - on off). And your not adding jars of marshmallow correct, you're melting mini marshmallows? I find that in the winter when the air is dry I use a lot less powdered sugar than in the summer when there's so much moisture and humidity in the air. Another trick in dealing with sticky fondant - grease your fingers with Crisco. Makes the job so much more pleasant.

Yep, Grease my bowl, add 1 bag of marshmallows, sprinkle water, nuk it and add about 1 - 1 1/2 pounds of ps.

Works like a charm every time.  no measuring.

Oh and it has to be a 16 oz. bag of mini marshmallows not the 10.  

The first time I made it I was freaking out about how it looked. Eventually it all comes together though! Just keep adding the ps in until you get the right consistency. I never measure it out.

AThank you all. I added more icing ( it's much more than the recipe says) it doesn't stick anymore but there's no elasticity to it anymore? I'm freaking out again

Add some shortening to it.  Warm the fondant up just a little in the micro, and  knead it in.

I always add about a tablespoon of corn syrup.  It helps to keep it more elastic.
 

jessicakes blog has a recipe for marshmallow fondant that works really well.