2 packets Knox gelatin (1/2 ounce total)
3 egg whites
2 rounded tablespoons agave syrup (substitute honey or corn syrup)
1 C sugar
flavors of your choice: generally I try for 4 tsp flavoring per half recipe ratio (either of liquid flavorings like extracts or by dissolving 4 tsp of a powder like cocoa in a little water), but it is possible for that to be too strong so start off with less of strong extracts like mint.
flavor ideas: orange extract, rose water, cocoa powder, mint extract, coconut extract, caramel, butter flavoring
coatings of your choice: powdered sugar is a good standard, or granulated sugar if you like a little crunch on the outside
Line 2 loaf pans with parchment paper or wax paper. If only making one flavor, line a square 8x8 inch pan with paper. Use a sieve to line the paper with a layer of powdered sugar. This will help you to remove the sticky marshmallow from the paper later on.
Soften the gelatin powder by placing 3-4 tablespoons of water in a small bowl, and sprinkling the powder over the surface of the water. Set aside to let it thicken. If the powder does not all get soaked up by the water, you may sprinkle a teaspoon more of water on top, but not too much - you don't want to add much liquid to the mixture. It is okay if your gelatin looks like a grainy, cloudy clump of gelatin in the bowl - just let it sit, and it will be dissolved when you add it to the rest of the ingredients.
Have the egg whites ready in the bowl of a stand mixer or mixing bowl if you're going to use an electric hand-mixer.
Combine the agave syrup, sugar, and 6 T water in a medium saucepan. Bring to a simmer over medium heat, stir to dissolve, and keep at a simmer for 8 minutes. Remove from heat.
Add the gelatin to the syrup, and stir with a wooden spoon until completely dissolved. There will be an immediate foaming up when you add the gelatin, but that should die down as you stir. Cover to keep warm.
Beat the egg whites until soft peaks just begin to form. With the beater still on, add the hot syrup in a slow, steady stream, and keep whisking until the mixture cools down to just above room temperature. You may stop the mixing before it cools down if it takes on a nice, white, lightly marshmallowy appearance and texture, which usually appears after 10-15 minutes of mixing. The longer you mix it, the stiffer the marshmallows will be. The mixture should not be stiff marshmallow consistency when you stop mixing, but it should be thick enough to be picked up by a spoon so that it follows the spoon on its own. It will thicken more as it sits out for the next day.
Transfer half of the egg white mixture into a second mixing bowl, and whisk in the flavoring quickly. Add the second flavoring to the remaining mixture and whisk it in without overbeating. Add a drop or two of food coloring if so desired.
Pour each of the mixtures into a different prepared loaf pan and even out the surface with a spatula. Sprinkle some powdered sugar over the surface to enable easier handling later, and cover lightly with a sheet of parchment paper (without pressing on the surface) and let stand somewhere cool for 24 hours.
Place the coatings of your choice in wide, shallow bowls.
Have a mug/glass of hot water ready. Lift the parchment paper to remove the marshmallow from the pan, and place on a cutting board. Carefully peal the paper off the sides of the marshmallow by pulling on the paper and using a knife to push the marshmallow off. Cut the marshmallow into squares, dipping the knife in the hot water between cuts.
A few at a time, transfer the squares into the bowl of coating and toss in the coating. They will be quite sticky, so handle them lightly (I use spoons or the knife to manipulate the squares), and make sure they are well coated before you set them aside to dry. I like to put them on a baking pan lined with parchment or wax paper.
Leave them out to dry for 2 or 3 hours, flipping them halfway through. It is important to flip them, as the bottom side will remain wet if not exposed to the air. I prefer to let them set out for a day or more, as this allows them to grow chewier the way I like them. If you put them in an air-tight container after 2 or 3 hours, they will remain fairly soft. You can place them in a fine sieve and shake them out in order to remove some of the extra coating prior to packaging them away. I actually enjoy letting them dry with excess powdered sugar on them, as the sugar forms small crisp clumps of sugar on the surface of the marshmallow, which adds a little crunch on top of the chewy lightness. These should keep for a few days in an air-tight container.
The last step is one of my favorites: chocolate dipping. Once the marshmallows are dried to your preference, you can melt some chocolate (dark, white, whatever!) and dip the finished squares in it, again setting them to dry on parchment paper. I usually melt chocolate in the microwave for convenience's sake, even though that is not the best for the chocolate, but you have to be careful to not heat the chocolate chips or squares in the microwave for any longer than 30 seconds at a time, and stir well between heating bouts. It is easy to burn chocolate in the microwave if you heat it for any longer at once.
It is also possible to cut the marshmallow on the second day with cookie cutters, or to pipe it into shapes on the first day with a piping bag, so get creative!
Serve plated, package as a gift for friends with individual squares in candy papers, wack out your blood sugar and eat them all yourself, make a pyramid of guimauve, or think of your own ideas.