Stir together the sugar, honey water, and salt in a small saucepan over high heat. Bring to a boil, stirring occasionally, until the mixture reaches 240°F on a candy/fat thermometer.

Place the egg whites in the bowl of a stand mixer fitted with a whisk attachment. Start whipping the egg whites to soft peaks on medium speed. You want the egg whites at soft peaks by the time the syrup reaches 240°F. When the syrup is 240 deg immediately remove from the stove and reduce the mixer speed to low and slowly drizzle the syrup into the egg whites. Increase the speed to medium high and whip until the marshmallow crème is stiff and glossy and mixer bowl is cool to the touch, about 7 minutes. Add in the vanilla and whip 2-3 minutes more until the mixture is stiffened back up again. Use immediately or refrigerate stored in an airtight container for up to 2 weeks.