Preheat oven to 350˚F. Line a cookie sheet with a piece of parchment paper. Set aside.
Beat egg yolks and sugar until lemon color. Add in water, salt, flour, powder, vanilla and cocoa.
Beat at high speed for 10 minutes.
Spread evenly onto prepared cookie sheet. (Batter will be quite runny.)
Bake for 20 minutes.
While this is cooking, prepare a tea towel that is a bit bigger than the cookie sheet. Sprinkle 1/4 cup cocoa all over the tea towel.
When cake comes out of the oven dump it right onto the prepared tea towel.
Peel off the parchment paper and roll the tea towel up together in a tight roll.
Wrap the whole thing in saran wrap and put it in the fridge to cool.
While you are waiting, make the ganache by microwaving the chocolate chips and cream together. 1 minute or Just until they will melt together.
Let this sit on the counter until it thickens and cools a bit.
When your cake roll is cooled, carefully unroll it.
Spread the two jars of marshmallow over the cake.
Sprinkle the graham cracker crumbs and then pour the chocolate ganache over top. (If it is too hot it will just run right off so it needs to be a little bit cooler but not too much or it will harden up.)
Carefully roll the whole roll together again and wrap in saran wrap and put in the fridge for at least 1 hour.
When ready to serve, unwrap and slice into slices.