Place the shortening in a small bowl, you’ll need to dip into throughout the entire process.
Grease a microwave-safe bowl, the electric mixer bowl, the paddle attachment and a spatula with shortening.
Pour the marshmallows, 3 tablespoons of water and the extract in the microwave-safe bowl.
Melt the marshmallows in the microwave in 30 second increments. Stir with the greased spatula in between.
Continue until the marshmallows are completely smooth—2-3 minutes.
Pour the marshmallows into the greased mixer bowl. Start the mixer on low and slowly add the entire bag of powdered sugar. Mix until the mixer starts to struggle. There will still be plenty of dried clumps in the bowl.
Grease a clean work surface and your hands. Dump the mixture out on the surface, clumps and all. Start kneading and re-grease hands as needed.
Knead for several minutes until the mixture is clump free. At this point, if it seems to be dry and rips when you pull it, add a little more water, 1 teaspoon at a time, until the fondant is soft, pliable and can stretch a little ways when you pull on it. *When you add the water, it is going to seem like a mistake for a moment, but re-grease your hands and keep kneading. The water will absorb into the fondant.
Now, grease the whole ball and wrap with plastic wrap. Place the wrapped ball in a large zip bag and squeeze out all the air before sealing. Let it sit overnight to improve the texture and elasticity. *You can use it immediately in a “cake emergency” but it’s better to wait. *It’s best to color fondant right before using so the color doesn’t fade. Drop a few drops of food coloring on the fondant and knead in.
Once it has sat overnight, sprinkle a clean work surface, and your hands, with cornstarch. *Some people use more powdered sugar for this, but they risk adding clumps to their perfectly smooth fondant. Cornstarch doesn’t clump.
If rolling out for a cake, rub cornstarch on the rolling pin and roll until just over 1/8-inch thick. Make sure to measure the cake and sides accordingly. Drape over a frosted cake and gently smooth any bumps or creases. Carefully cut the excess fondant around the bottom.
If using for molding, HAVE FUN! It molds just like play dough. If wrapped well, it will keep at room temperature for a long, long time.