Separate egg whites from yolks. (Save yolks for another recipe.)
In a cold mixing bowl and with cold beaters, beat egg whites into stiff peaks.
Transfer the stiff-peaked whites to another bowl, cover, and refrigerate.
Clean the mixing bowl and beaters (unless you have a spare!)
Liberally grease a 9x13 pan (you can use the wrapper for the butter in the graham cracker recipe below) and liberally dust the greased pan with icing sugar.
Place 3.5 packets of gelatin and .5 cup of the cold water into the bottom of the mixing bowl of a stand mixer and let sit.
The kids will enjoy watching it become a gooey sticky alien shape.
Fill a thick-bottomed saucepan with that other .5 cup of cold water, the granulated sugar, corn syrup and salt.
Stir over low heat until the sugar is dissolved.
Then, boil over medium heat without stirring for approximately 10 minutes.
Watch for the mixture to bubble, thicken, and clear.
When a candy thermometer reaches 240F, remove from heat and pour on top of the thickened gelatin.
Mix the gelatin and sugar mixture on low for a few moments. It will be hot, so best have the adult take charge.
Gradually adjust the mixer to higher and higher speeds and let mix for 5-6 minutes.
Watch it circle round! The sugar will turn into a marshmallow fluff before your Irish eyes!
Add vanilla & mint extracts*, green food colouring (optional), and stiffened egg whites, and mix for another minute.
Use a spatula to guide the fluff into the prepared dish. It usually spreads out evenly on its own.
Using a wire strainer or a mesh tea ball dust the top of the marshmallow wtih additional icing sugar.
Refrigerate for at least two hours, until stiffened.
Loosen the edges of the marshmallow with a butter knife.
Overturn the marshmallow onto a cutting board.
Use a mini- or small-sized shamrock cookie cutter to cut out of the marshmallows,
OR, cut the marshmallows into cubes with a large knife.
Dredge the sticky sides of the individual marshmallows in a bowl of icing sugar.