In a microwave safe bowl, melt marshmallows and water for 35 seconds.Remove from microwave and mix. Repeat until the marshmallows are melted which will take about 2 minutes to melt them all.
Remove from microwave. Grease a cutting mat or counter to mix and knead the fondant.
Pour the powdered sugar onto the mat. Pour the melted marshmallow mixture into the powdered sugar. Rub the solid shortening on your hands and and start to knead. The marshmallows may be hot so be careful!
Continue kneading and adding all the remainder of the powdered sugar.
If your Fondant is dry or cracks, add a little more water.
You will probably need to grease your hands several times during this process.
Continue to knead until all the powdered sugar has been mixed into the fondant and you don’t see any more little powdered sugar balls hanging around.
Rub disc with Crisco then, wrap it in plastic wrap and place it into a Zip Lock bag removing all the air. Store in the refrigerator for up to 2 weeks before use.