Apple cake

Preheat the oven to 180°C. (350˚F) Grease a cake pan and line it with baking paper. In a large bowl, break the four eggs with the sugar and beat until they have tripled in volume and become fluffy. Sift the self-rising baking flour and add it to your egg mixture. Fold this over, preserving as much air as possible. Add the melted (and slightly cooled) butter and mix until combined. Add cinnamon, pinch of salt and vanilla extract. Add the diced apple to the batter and gently fold them into the batter so that the apple pieces are evenly distributed. You can roll the apple pieces through some