Evenly & generously spray a 9 x 13-inch baking pan and set aside. Lightly powder the baking pan with powered sugar.

In a bowl of a stand mixer combine gelatin and the 2/3 cup water, fit with whip attachment and set aside.

In a heavy saucepan combine sugar and ¾ cup water (2) and cover with a lid. Boil for 3 minutes and remove lid. Attach a thermometer on side of pan and boil until syrup reaches 240°F. Do not stir syrup as this may cause it to crystallize.

Remove from heat, engage mixer in medium speed and while whipping pour hot syrup in a slow and steady stream onto whipping gelatin. Once all combined engage mixer in high speed. Add salt.

Whip until mixture feels lukewarm and looks like marshmallow fluff, about 8-12 minutes. Add vanilla. Stop mixer and scrape marshmallow into prepared pan. Spread evenly. Dust with a partial amount of powdered sugar.

Allow to cool, preferably overnight while covered with plastic food wrap.

Next day remove from pan and cut into desired size, toss generously into powdered sugar.