Recipe and photography courtesy of Chef Virginia Willis.
Heat the oven to 200°. Line two baking sheets with parchment paper or a nonstick silicone baking mat; set aside. Fit a piping bag with a star tip. Set aside.
Using the bowl of an electric mixer fitted with a whisk attachment, whisk egg whites and salt on medium speed until soft peaks form.
Increase the speed to medium high. Gradually add the sugar, whisking until stiff, glossy peaks form. Paint peanut butter down one side of the interior of the piping bag and jam down the other. Fill with meringue. Pipe swirled dollops onto the prepared baking sheet. Once the bag is emptied, repeat with remaining meringue, peanut butter, and jam.
Transfer to oven and bake on center rack of oven until crisp and dry, about 45 minutes. Turn the oven off and leave meringues in the oven at least 2 hours and preferably overnight.