Preheat oven to 350 degrees.
On two pieces of parchment paper, draw circles 9 inches in diameter and place parchment paper upside-down on baking sheets.
In a stand mixer or in a large bowl with hand mixer, beat the egg whites until soft peaks begin to form, about 2 minutes. Beat in sugar slowly until egg whites turn shiny and stiff, about 6-8 minutes.
Fold chopped dark chocolate and cocoa gently into the egg whites until evenly dispersed.
Dab a small amount of meringue onto each corner of the parchment paper in order to secure papers to the pans.
Divide the meringue into two equal portions and form mounds within both of the circles on the parchment paper. Smooth sides and tops of meringue mounds with a spatula.
Put meringue in the oven at 350 degrees and then immediately turn oven temperature down to 300 degrees. Bake for about one hour, until meringues are crisp on top, but squishy underneath.
Turn oven off and open door a crack to let meringues cool completely for about two hours (you can remove it sooner but will have a higher risk of the pavlova cracking).
Once cooled, invert one meringue onto a cake plate and cover in marshmallow whipped cream. Sprinkle graham cracker crumbs on top.
Invert second meringue on over whipped cream and graham crackers and top with more whipped cream and graham cracker crumbs.
Pour chocolate ganache over the whipped cream and let drizzle down the sides. Top with additional mini marshmallows.