Preheat the oven to 180?C/gas mark 4. Butter two Victoria sponge cake tins and line the bottoms with greaseproof paper.

Using an electric whisk or stand mixer, beat together the caster sugar, soft brown sugar, eggs, and vanilla for about four minutes until creamy. Gradually add vegetable oil and mix well.

Sift in flour, cocoa powder, baking powder, and bicarbonate of soda, stirring well with a metal spoon. Add a pinch of salt and plain yoghurt, mixing well.

Divide the batter equally between the prepared tins and bake for 30 minutes, checking after 25 minutes with a cocktail stick for doneness. Once done, remove from oven and let cool.

To make the filling, beat room temperature butter until soft and fluffy. Gradually add icing sugar and continue mixing until fully incorporated. Stir in caramel sauce and a pinch of sea salt.

Once the sponges are completely cooled, slice each in half horizontally to create four layers. Place the first layer on a serving plate and spread one third of the buttercream over it. Repeat with the remaining layers, finishing with the final sponge on top.

To prepare the chocolate fudge topping, melt the chocolate in a glass bowl set over a pan of boiling water. Once melted, remove from heat and stir in cream and caramel. Allow to cool before spreading over the top layer of the cake.

Decorate with fudge pieces or sprinkles, and reserve any leftover chocolate fudge for drizzling or dipping.