Meringue: Preheat oven to 100 degrees C. Line a baking tray with baking paper.
In a bowl whisk the egg whites, sugar and salt until very stiff. At the end add the food colouring. Place on the baking tray and flatten. Bake for 80 minutes until the meringue is firm and dry. Allow to cool, then remove from baking tray and peel off the baking paper. Finely crumble the meringue.
Sponge: Increase oven temperature to 200 degrees C. Grease a springform cake tin.
Separate the eggs. Whisk the egg yolks with the sugar until creamy.
In a saucepan heat the Chestnut puree with the butter until the butter has melted. Gradually stir the chestnut mixture into the egg yolks along with the vanilla.
Stir in the cornflour and baking soda until well combined.
Beat egg whites until stiff then fold in. Pour the batter into the prepared springform cake tin. Bake in the preheated oven for 30 minutes.
When cooked take the cake out the cake tin and cool on a wire cooling rack. Carefully cut the cake horizontally into two equally thick pieces.
Filling: In a saucepan heat he chocolate and cream just until the chocolate has meltedd, do not boil. Allow to cool then chill for at least 2 hours in the refrigerator.
Combine the chocolate cream with the cream stabilizer, if using.
Place half the chocolate cream on the base of the two cake halves.
Sprinkle the chocolate cream with all the meringue crumbs.
Gently press half the meringue crumbs into the chocolate cream.
Brush any crumbs that fell off the cake back into the container with the remaining meringue crumbs. Further crush the meringue crumbs then sift through a sieve to collect the fine crumbs and remove the larger lumps.
Place the cake top onto the cake, cut side down. Cover with the remaining chocolate cream.
Create the hearts by using one teaspoon of the meringue crumbs and a heart shape biscuit cutter.
Press the cutter firmly into the cake and sprinkle the crumbs evenly. Remove the cutter to reveal the hearts.