Preheat the oven to 180°C (350°F) and grease two 20cm round cake tins.
In a large mixing bowl, cream together the softened butter and golden caster sugar until light and fluffy.
200 g golden caster sugar, 200 g unsalted butter
Beat in the eggs, one at a time, ensuring each egg is fully incorporated before adding the next.
4 large eggs
In a separate bowl, sift together the self-raising flour and cocoa powder.
200 g self-raising flour or plain flour with 2 teaspoons of baking powder, 50 g cocoa powder
Gradually add the dry mixture to the wet mixture, alternating with the milk. Mix until well combined.
100 ml milk
Divide the batter evenly between the prepared cake tins.
Bake in the preheated oven for 20-25 minutes or until a skewer inserted into the center of the cakes comes out clean.
Remove the cakes from the oven and let them cool in the tins for 10 minutes before transferring them onto a wire rack to cool completely.
Once the cakes are completely cooled, spread a layer of melted dark chocolate on one cake and sandwich the other cake on top.
100 g dark chocolate or milk chocolate