Melted marshmallows are used to make bar cookies, fondant, frosting, candies and other sweet treats. Marshmallows can be melted in either the microwave or the stove-top. No matter which method you use, the key is to stir the marshmallows frequently. Stirring helps to ensure they melt smoothly, and prevents the marshmallows from burning. You will also want to add a few tablespoons of water, butter or oil to the marshmallows while melting. This allows the marshmallows to be smoothly incorporated into the melted marshmallow mixture.
Place the marshmallows in a large microwave-safe bowl. The marshmallows will expand when they are heated, so the bowl should be three to four times as large as the amount of marshmallows you are melting.
Turn on the microwave, set to high, for 30 seconds. Take the bowl out of the microwave and stir the marshmallows. Scrape off any marshmallow stuck to the side of the bowl and incorporate it into the mix.
Return the marshmallows to the microwave and cook for another 30 seconds. Continue the cycle of cooking for 30 seconds, then pausing to stir, until the marshmallows are smooth and melted.
Fill the bottom of a double-boiler with water and bring to a boil.
Add the marshmallows to the top insert of the double-boiler, and place the insert on top of the boiling water. Turn the heat down to keep the water at a simmer.
Stir the marshmallows constantly until melted.