• Preheat the oven to 200C/180C Fan/Gas 6. Line 4 x 8" cake tins.
• In a large bowl, or the bowl of a stand mixer, combine the flour, baking powder, baking soda, cocoa powder, sugar.
• Get the kettle on – essentially we are going to make a hot chocolate. Combine the boiling water, hot chocolate powder and milk in a mug. Set aside. 
• Make a well in the dry mix, and add the eggs, syrup and oil. Once thoroughly combined, slowly pour in the hot chocolate mixture until it has all been incorporated. The batter will be fairly thin. 
• Pour the batter into the tins and bake for 25 minutes, until a skewer inserted comes out clean. Let cool on a wire rack.

For the Frosting

• Once cool, make the frosting: beat the butter on high with an electric mixer. Add half the icing sugar and the caramel and combine for several minutes until combined. Add the remaining icing sugar until you reach your desired consistency. 
• Layer up the cakes on a board: start with one of the cake rounds, top with buttercream and spread evenly (optional: add extra caramel in the middle). Repeat with each layer.
• If covering the whole cake: Once you've layered up, spread a good amount all over the cake, don't worry too much about keeping it smooth at this point. Let it chill in the fridge for about 30 minutes.
• Add another thick layer of buttercream on the cake, smooth over the top with a spatula and smooth out and around the edges with a tall cake scraper. A cake turntable will make this easier!
• Add any extra decorations (I used some chocolates cut up) and serve!