A light, luscious hazelnut meringue cake with chocolate-coffee filling is a dream dessert after a buffer. To make a taller cake pipe three 8-inch circles and fill as directed. This looks spectacular but is harder to cut. Preheat oven to 225F (110 °C). Line 2 baking sheets with parchment paper or foil. Draw a 10-inch circle on each sheet. Turn sheet over so pencil will not come off on meringue. Combine hazelnut and cornstarch making sure there are no lumps. Place egg whites in bowl of electric beater and whisk until soft peaks form. Gradually sprinkle in sugar, beating until stiff peaks form and mixture is glossy. Beat in lemon juice. Sprindle nut mixture over the whites and quickly fold in. Either gently spread or pipe meringue into the two circles. Place in oven and bake for 2 to 2 1/2 hours, until meringue is dry but not coloured. Cool on baking sheet. Remove from parchment paper and store at room temperature in an airtight tin for up to three weeks. Mocha Filling: Stir together coffee and Kahlua until coffee is dissolved. Beat whipping cream until it thickens and holds its shape. Beat in icing sugar and sifted cocoa. Add coffee mixture and beat until cream is stiff. Do not overbeat; cream should be thick and smooth. Refrigerate until ready to use. To assemble, spread half of cream on one layer. Top with second layer and remainder of cream. Decorate with chocolate curls, chocolate coated coffee beans or spread a doily on cream and sifted cocao over.