Preheat oven to 350°F. Grease and line 9" round pan with removeable bottom. Mix chia seed meal and warm water. Set aside for 15min. Melt butter and chocolate, mix and set aside to cool. Beat egg whites and 1/3 cup sugar to soft peaks. Beat egg yolks and 2/3 cup + 2 tbsp sugar until pale. Beat in chocolate mixture, then hazelnut meal, then chia seed mixture. Finally, fold in egg whites. Bake 50min.