Prep pans: Line three baking sheets with parchment paper. With a pencil, draw 5 circles 9 inches in diameter on the parchment paper (trace around a cake pan or large saucepan).
For cakes: In a large clean bowl, whip the egg whites until soft peaks form.
Gradually add the sugar and beat until stiff peaks form.
Mix together the icing sugar, cinnamon and corn starch, along with the ground hazelnuts, then carefully fold them into the egg white mixture.
Divide the mixture evenly between the 5 circles, and spread the meringue out to the edge of the drawn circle. Bake at 250°F for 3 to 4 hours until the meringue is completely dried out. Cool on wire racks.
For filling: whip the cream and sugar until stiff. Spread whipped cream over all of the (cooled) meringue layers, then stack the layers on top of one another.
Use the remaining whipped cream to spread around the outside edge of the cake.
To decorate: lightly dust cake with cocoa, then cover with chocolate curls (use a vegetable peeler to create curls along the chocolate squares).
Notes
Assemble cake just before serving, as the meringue will soak up moisture from the whipped cream and start to get soggy if left for too long.
