Fluffy, bouncy vanilla marshmallows with a gentle sweetness and a hint of salt, perfect for s’mores, hot chocolate, or gifting. Made without corn syrup, they set up into pillowy squares dusted in powdered sugar and starch for a classic, nostalgic treat.
Lightly grease a 9×9 or 10×8-inch baking dish and line it with parchment paper. In a mixing bowl or stand mixer with whisk attachment, add 1/2 cup cool water, sprinkle gelatin over the top, whisk, and let bloom for about 10 minutes.
In a medium saucepan, combine sugar, salt, and the remaining 1/2 cup water. Heat over medium until sugar dissolves, then increase to medium-high.
Bring to a gentle boil without stirring until the mixture reaches 240°F (soft ball stage) on a candy thermometer.
Carefully pour the hot syrup into the bloomed gelatin while mixing on low speed. Gradually increase to high and beat 8–10 minutes until thick, glossy, and tripled in volume.
Add vanilla extract and mix just to combine. In a separate bowl, whisk together powdered sugar and cornstarch (or arrowroot).
Quickly spread the marshmallow mixture into the prepared pan with a greased spatula. Dust the top with some of the powdered sugar–starch mixture.
Let set at room temperature at least 3 hours or overnight until firm.
Turn the slab out onto a cutting board, peel off parchment, dust the top again, and cut into squares with a sharp knife or kitchen scissors.
Place cut marshmallows in a bowl and toss with more powdered sugar–starch mixture to coat and prevent sticking. Store in an airtight container at room temperature.