Mix cool water and gelatin in a small pot. Let sit 5 minutes, then warm until it gently simmers.
In a stand mixer or mixing bowl add salt, syrup and vanilla. Add the water/gelatin mix and turn on low then increase to high speed. Can use a hand mixer.
Beat until soft peaks form, which takes me about 5 minutes.
Do not over beat or they will be ugly and won't spread into the pan well!
Lin a 9x13 pan with parchment paper. Dust the paper liberally with cornstarch, powdered sugar, cocoa powder, or shredded coconut.
Carefully spread the mixture into the pan.
Dust the top with more of the same and let rest several hours before cutting.
Notes
I like to cut, dust with more of what I did to start, and leave spread out on a cookie sheet to air dry a bit so they don't sweat in a closed pan. They can be left air drying up to 2 days, and then into a container and they will last a few more days. I don't actually know how long they last because we eat them too fast!