I made some for Darcy's 4th birthday and it was fun and a lil' bit messy!
Prepare your 13x9 glass pan or jelly sheet by spraying with oil and dust with powdered sugar.
First step is to heat the sugar, water and agave nectar (I used agave in place of corn syrup or rice syrup, which I have tried before) in a large heavy-bottomed pan (it will bubble up so watch it). You will need to heat this mixture to 240 degrees, which takes about 12 minutes.
Step Two: While your sugars are heating up, take your gelatin (I used beef gelatin from the health food store) and sprinkle it over cold water in your mixer bowl. This will give it time to soften.
|I used vanilla agave nectar, so I didn't add more vanilla, although you can if you want to|
Refrain from scraping the bowl. Just tap the mixing paddle on the side of the bowl to loosen the marshmallow.
This is the messy part - dump the marshmallows onto the prepared dish while they are still hot. You won't want to spread the mixture, just pour it around the dish. If you have to spread it make sure and use an oiled spatula or oil your hand and press down.
Try not to get the gooey stuff all over you in the process,
Sprinkle with powdered sugar and cool for a few hours in the refrigerator.
To cut the marshmallows you can use a sharp chef's knife or an oiled pizza wheel. Cut into the size you prefer. I cut mine into graham cracker sizes.
To make s'mores without a campfire, you can place a marshmallow on a cracker and microwave for 10 seconds, sprinkle with a few chocolate chips and top with another graham cracker. Eat the ooey gooey goodness and rinse to clean.
Recipe here: http://smittenkitchen.com/2009/06/springy-fluffy-marshmallows/
P.S. You do not have to add the egg whites to make this recipe work. I tried it with the egg white and I think it made it more sticky than anything else.