Preheat oven to 180°C. Line a 24cm round cake pan with grease proof paper. Place a box of Dr. Oetker Nona Sponge Cake Vanilla, 5 eggs and 100ml water in a mixing bowl. Mix at medium speed for 4 minutes.
Add in 100g melted butter and mix at low speed for 1 minute or until batter is light and fluffy, then bake at 180°C for 45 minutes
For the buttercream, place in vanilla flavour, softened butter, salt, icing sugar, lemon juice and beat until light and creamy. Set aside.
For the apple compote, peel and quarter the apples, remove the core then finely dice them. Caramelise the sugar in a pan on a medium heat. Add the apple, cinnamon and few drops of vanilla flavour, cover and cook on a medium heat, stirring occasionally, for approx. 10 minutes or until soft.
Meanwhile, slice the sponge cake into three layers horizontally. Place one of these layers on a cake board. Spread apple compote on the first layer, lay the second layer on top and gently press down. Spread 4 tbsp of buttercream onto this layer then lay the third layer on top. Leave the cake to chill for approx. 1 hour.
Melt cooking chocolate with microwave oven or “double-boil”. Place the emoji template in a clear plastic sleeve. Fill the piping bag with melted cooking chocolate and pipe onto the template, let it set for 10 minutes. Spread the rest of the buttercream onto the top and sides of the cake. Decorate the emoji onto the side of the cake