Preheat your oven to 225°F and line a large baking sheet with parchment paper.

Beat egg whites, cream of tartar, and salt in a glass bowl until soft peaks form.

Gradually add superfine sugar while beating on high speed until the meringue is stiff and glossy.

Gently fold in the sifted cocoa powder until a dark, marbled effect is achieved.

Pipe or spoon 6 large, wide bowls onto the baking sheet, using a spoon to create a deep, wide well in the center of each.

Bake for 90 minutes, then turn off the oven and let the meringue bowls dry inside for at least 2 hours.

Melt dark chocolate chips with heavy cream, vanilla, and espresso in a double boiler until a thick, pourable ganache forms.

Place mini marshmallows in a small oven-safe dish and broil for 1 minute until charred and gooey.

Pour the warm chocolate lava into the center of each meringue bowl, top with toasted marshmallows, graham crumbs, and flaky sea salt.