Preheat the oven to 180º C. Grease and line a 20cm round springform cake tin with parchment paper.Place the castor sugar, butter and sea salt in a large based pan. Cook for about 12-15 minutes until all the juices have evaporated and the apples are caramelised, with good colour. It’s important to keep turning the apples to prevent burning.Now deglaze the pan with the cognac and reduce down on a high heat until the apples are sticky once more. Set side to cool.To make the batter, cream together the butter and castor sugar. Add the eggs one at a time and whisk until until creamy. Now add the lemon zest and vanilla extract. Sift the flour, ground almonds and salt together. Add the dry ingredients and milk to the butter mixture in two stages. Beat slowly to prevent over-mixing.Arrange the cooled apples on the base of the cake tin. Spoon the batter over the apples and smooth the top. Tap the cake tin firmly on the counter before baking for 30-35 minutes. Check if finished after 30 minutes. Rest the cake in the tin for 15 minutes before unclipping the sides. Leave to cool for an additional 10 minutes before turning over onto a serving plate.Recipe reprinted with permission of bibbyskitchenat36. To see more recipes, please click here.To receive quick and convenient weekday recipes, join our Easy Weekday Meals mailing list, and for up-to-date trending food, restaurant and wine news subscribe to our Editor’s Weekly newsletter.