Even though it was the first warm day in weeks...this was how one of my little guys wanted to enjoy his marshmallowy goodness! (Kind of looks like pats of butter floating around in there...)
About 1 cup potato starch (found in the kosher foods section of supermarkets) or cornstarch
2 tablespoons light corn syrup
2 1/4-ounce packets unflavored gelatin
3 large egg whites, at room temperature
3/4 cup cold water
1 tablespoon pure vanilla extract
1 1/4 cups plus 1 tablespoon sugar
Line a rimmed baking sheet -- choose one with a rim that is 1 inch high -- with parchment paper and dust the paper generously with potato starch or cornstarch. Have a candy thermometer at hand.
Put 1/3 cup of the water, 1 1/4 cups of the sugar and the corn syrup in a medium saucepan over medium heat. Bring the mixture to a boil, stirring until the sugar dissolves. Once the sugar is dissolved, continue to cook the syrup -- without stirring -- until it reaches 265 degrees F on the candy thermometer, about 10 minutes.While the syrup is cooking, work on the gelatin and egg whites.
In a microwave-safe bowl, sprinkle the gelatin over the remaining cold water (a scant 7 tablespoons) and let it sit for about 5 minutes, until it is spongy, then heat the gelatin in a microwave oven for 20 to 30 seconds to liquefy it. (Alternatively, you can dissolve the gelatin in a saucepan over low heat.)
Working in the clean, dry bowl of a stand mixer fitted with the whisk attachment or in another large bowl with a hand mixer, beat the egg whites on medium-high speed until firm but still glossy -- don't over beat them and have them go dull. As soon as the syrup reaches 265 degrees F, remove the pan from the heat and, with the mixer on medium speed, add the syrup, pouring it between the spinning beater(s) and the sides of the bowl. Add the gelatin and continue to beat for another 3 minutes, so that the syrup and the gelatin are fully incorporated. Beat in the vanilla.
Using a large rubber spatula, scrape the meringue mixture onto the baking sheet, laying it down close to a short end of the sheet. Then spread it into the corners and continue to spread it out, taking care to keep the height of the batter at 1 inch; you won't fill the pan. Lift the excess parchment paper up to meet the edge of the batter, then rest something against the paper so that it stays in place (I use custard cups).Dust the top of the marshmallows with potato starch or cornstarch and let the marshmallows set in a cool, dry place. They'll need about 3 hours, but they can rest for 12 hours or more.
Once they are cool and set, cut the marshmallows with a pair of scissors or a long thin knife. Whatever you use, you'll have to rinse and dry it frequently. Have a big bowl with the remaining potato starch or cornstarch at hand and cut the marshmallows as you'd like -- into squares, rectangles or even strips (as they're cut in France). As each piece is cut, drop it into the bowl. When you've got 4 or 5 marshmallows in the bowl, reach in with your fingers and turn the marshmallows to coat them with starch, then, one by one, toss the marshmallows from one hand to the other to shake off the excess starch; transfer them to a serving bowl. Cut and coat the rest of the batch.
SERVING: Put the marshmallows out and let everyone nibble as they wish. Sometimes I fill a tall glass vase with the marshmallows and put it in the center of the table -- it never fails to make friends smile. You can also top hot chocolate or cold sundaes with the marshmallows.
STORING: Keep the marshmallows in a cool, dry place; don't cover them closely. Stored in this way, they will keep for about 1 week -- they might develop a little crust on the outside or they might get a little firmer on the inside, but they'll still be very good.