Method

1. Preheat the oven to 165°C (325°F), Gas mark 3. Line the bases of the cake tins with rounds of baking parchment, brush the sides with melted or soft butter and dust with flour.
2. To make the cake, place the butter in a mixing bowl and beat until very soft. Add the sugar and one of the eggs and beat again, then add the other egg and mix. Sift the flour, cocoa powder, baking powder, bicarbonate of soda and salt into a separate bowl and set aside. Measure the buttermilk and set aside also.
3. Now, start the meringue. Place the egg whites in a bowl and whisk until frothy using an electric food mixer or hand-held electric beater. Add in half of the sugar and continue whisking until the mixture holds stiff peaks. Turn off the whisk and fold in the remaining sugar.
4. Next, go straight back to the cake. Fold in the sifted dry ingredients and the buttermilk, then divide the mixture between the two cake tins, making sure they are level. Divide the meringue between the two cakes and spread out evenly over the cakes.
5. Cook in the oven for 1 hour or until a skewer inserted into the centre comes out clean.
6. Take out of the oven and allow to sit in the tin for 15-20 minutes before loosening around the sides with a small, sharp knife, removing the cakes from the tins and allowing to cool completely meringue side up.
7. When ready to assemble, whip the cream until it just holds stiff peaks, then place one of the cakes (save the best cake for the top) on a cake stand. Spread the whipped cream over the top, then sit the second cake on top of the cream. Dust with icing sugar and serve.

https://www.rte.ie/lifestyle/recipes/2014/1126/743490-chocolate-meringue-cake/