In a medium to large-sized bowl, sprinkle the gelatin over the cold water. Allow to sit for at least 5 minutes.
In a heavy bottom sauce pan, stir sweeteners and remaining (hot) water.
Heat sweeteners and water over high heat until the mixture reaches 240 - 245 degrees Fahrenheit, or the soft ball stage.
Gradually (and carefully :-)!), while mixing constantly, add the hot mixture to the water and gelatin mixture.
Slowly add the vanilla to the mixture while beating.
Beat on high until the mixture form stiff peaks (almost like beaten egg whites).
Pour into a lightly greased 8x8 pan. You can use whatever size pan you like to make either thick or thin marshmallows. The 8x8 pan will make pretty nice-sized thick marshmallows.
Allow marshmallow to set. Then cut into desired sized. This can take 6-24 hours (I've never had it take that long), but you can put them in the freezer to speed it up -- just don't forget they're in there :).
If desired, coat with cocoa, raw or toasted coconut, ground up nuts - have fun with your toppings!
Store in an airtight container and try to keep your kiddos out of them!