1. Preheat oven to 400 deg F/ 200 deg Celsius.
2. Beat egg whites until stiff and then gradually add confectioner's/icing sugar and beat until thick and glossy.
3. Fold in the cornflour and ground hazelnuts (or almond flour).
4. Draw 2 x 7 inch/about 6 inch circles on 2 pieces of baking paper. Divide meringue mixture between them, and spread neatly with a knife.
5. Bake for 2 hours or until meringues are crisp. Turn off oven, open door very slightly, and allow meringues to cool in oven.
6. CHOC MOUSSE: Place the broken chocolate and cream in a double boiler. If you are a dab hand at this, merely use a thick-bottomed smallish pot. Heat gently, stir until smooth, and allow to cool down.
7. Separate the eggs. Add egg yolks and stir until well combined.
8. Whisk the 2 egg whites until soft peaks form, and fold into chocolate mixture. Fold in cream, and refrigerate for 15 minutes.
9. Place one meringue carefully on a cake plate. Spread with the mousse and top with the remaining meringue.
10. Refrigerate for 3 - 4 hours or until mousse sets. Dust with cocoa before serving.