Spray baking pans with non-stick spray, line with parchment, and lightly spray parchment.
In a heavy-bottomed saucepot, combine 525g sugar and water, stirring just to wet sugar. Put egg whites and salt in the bowl of a stand mixer fitted with the whisk attachment.
Cook sugar over high heat until it begins to bubble vigorously. Rinse any sugar from the sides with a clean pastry brush dipped in cool water.
When the sugar begins to boil, begin to whisk the egg whites on high speed. When they foam, slowly begin adding the 50g reserved sugar ( ¼ cup – this is approximate because 50g is slightly less than ¼ c. Don’t stress; it isn’t that serious.). The salt and sugar will stabilize the egg whites.
Your sugar syrup should reach 235°F when the egg whites have reached a stiff peak. If your whites need more time, reduce the heat on the sugar. If your sugar needs more time, reduce the mixer speed to low but never turn it off. When the sugar reaches 235°F, increase mixer speed to high, and slowly pour the sugar into the bowl of the stand mixer in a steady stream being careful not to hit the whisk.
Squeeze excess water from the gelatin and add to the mixer.
Continue to whip on high until the mixture cools to body temperature. Add vanilla extract and beans.
Pour half into each prepared half-sheet pan and spread into an even layer with an offset spatula, working quickly before the marshmallow cools and thickens.
In a small bowl, whisk together the powdered sugar and cornstarch. Dust a thin layer over the top with a dry sifter. Allow cooling completely in a cool, non-humid place. Then wrap tightly in plastic wrap.
After cutting, toss the marshmallows in the powdered sugar/cornstarch mixture.
Video
Notes
Store in an airtight container away from heat and humidity. Never refrigerate or freeze.Yield: 100 marshmallows