• Preheat the oven to 200 °F. Line 3 half sheet pans with parchment paper. On one sheet of paper trace two 8" circles with a dark marker. Flip the paper so the marker side is down. Trace one circle on another piece of paper and flip that too.
• Sift together 8 oz confectioner sugar and 4 oz dutch process cocoa powder and set it aside.
• On medium speed, whip 9 large egg whites to soft peak. With the mixer running, very slowly add 14 oz granulated sugar. Increase the speed to medium high and whip to full peak. Remove the bowl from the mixer. Sift 1/3 of the cocoa mixture over the meringue and fold until mostly combined. Continue sifting and folding the rest of the cocoa in 2 increments. Fill a piping bag fitted with a 1/2" plain tip with the meringue.
• Pipe the meringue in a spiral to fill each of the circles. On the other sheet pan and on the pan with one circle, pipe long strips of meringue the length of the pan. Bake for 2-3 hours until completely dry. The strips will bake faster. Remove them from the oven and let the discs finish drying. The discs may take another hour or so.
• The meringues with be very light and completely firm when dry. They should easily release from the parchment paper. Cool completely before assembling the cake. The meringue can be made 1 day ahead and stored on tightly wrapped sheet pans.

Chocolate Mousse

• Whip 16 oz heavy cream to soft peak and set in the refrigerator while you prepare the other ingredients. Melt 10 oz semi-sweet chocolate and set aside.
• Combine 5 large egg yolks, half (2 oz) of the granulated sugar and 2 oz Grand Marnier in a mixer bowl. Set the bowl with the yolks over a pan of simmering water (make sure the bottom of the bowl doesn't touch the water). Whisk until the mixture is warm to the touch. Don't throw away the water, you'll use it for the whites too.
• Move the bowl to the mixer (or use a hand mixer) and whisk until the yolks are completely cooled and have lightened in color and texture. Whisk the melted chocolate into the yolk mixture. Fold the whipped cream into the chocolate base.
• Combine 2 large egg whites with the remaining 2 oz granulated sugar in a heatproof mixing bowl. Set the bowl over the pan of simmering water and heat to 160 °F, whisking constantly. Remove the whites from the heat and whip to full peak and completely cooled. Fold the whites into the mousse. If the meringue is too soft to spread allow it to firm up a little bit before assembling the cake. You want the mousse thick enough to spread, but not completely set.

Assembly

• Lift the cooled meringue strips off the parchment paper. Use a serrated knife to cut the strips into 2" segments.
• Place one of the chocolate meringue discs on a cake serving platter. Spread ⅓ of the chocolate mousse over the meringue. Place the second meringue on the mousse and top with half of the remaining mousse. Top with the last disc and ice the entire cake with the rest of the mousse.
• Cover the outside of the cake with the meringue sticks. You can place them in a neat pattern, or as I prefer you can just pile them on in a haphazard fashion. Refrigerate about 6 hours or overnight. The cake will keep in the refrigerator for 1-2 days.