Marshmallows are easy to make at home and have a great shelf life.
1/2 cup sifted confectioners’ sugar, plus more for dipping cookie cutter
1/4 cup sifted cornstarch
1/2 cup water, divided
1 tablespoon unflavored gelatin
3/4 cup plus 2 tablespoons sugar
1 cup light corn syrup
2 large egg whites
1/4 teaspoon cream of tartar
1 tablespoon vanilla extract
Special tools: candy thermometer
Line a jelly roll pan with aluminum foil or parchment paper. Whisk together confectioners’ sugar and cornstarch, then sift about half of the mixture evenly over the lined sheet. Reserve the rest.
Place 1/4 cup water in a small bowl and sprinkle gelatin over water; allow it to sit 5 minutes to “bloom” and soften. Meanwhile, place the remaining 1/4 cup water, 3/4 cup sugar, and corn syrup in a small saucepan, then stir to combine.
Bring the sugar mixture to a simmer over medium heat. Next, place egg whites in a clean, grease-free bowl and beat until frothy with an electric mixer. Add cream of tartar, then continue beating until soft peaks form. Using a candy thermometer, check sugar syrup; it should be nearing 240°. Beat 2 tablespoons sugar into egg whites, then continue beating until stiff peaks form.
When the syrup reaches 240°, remove from heat and whisk in the gelatin mixture until it dissolves.
With the mixer running, slowly add the syrup to the egg whites in a thin stream; keep the syrup from hitting the beaters or the sides of the bowl. Continue to beat until the mixture is thick, glossy, and cool, about 4 minutes. Beat in vanilla extract.
Scrape the mixture onto the prepared pan, quickly spreading to a 1/2-inch thickness with a spatula. Sift remaining sugar-cornstarch mixture over the top. Allow it to dry out at room temperature overnight. Dip a small star-shaped cookie cutter in confectioners’ sugar and cut out marshmallow stars. (They may be stored at room temperature in an airtight container up to 1 month.)