1. Preheat the oven to 170°C.
2. Grease and line your cake tins with baking parchment. Grease the paper and dust with flour shaking out any excess.
3. Sift the flour, cocoa powder, bicarbonate of soda and salt into a large bowl.
4. Put the chocolate, butter, sugar and honey into a pot and heat gently, stirring constantly, until the chocolate and butter have melted and sugar has dissolved. Set aside to cool slightly.
5. Put the milk, lemon juice, eggs and vanilla paste into a measuring jug and beat lightly with a fork until combined.
6. Pour the melted chocolate into the dry ingredients and stir with a wooden spoon until just combined.
7. Add the egg/milk mixture and beat gently with the spoon until you have a glossy, smooth batter.
8. Divide into the tins, starting with the smaller ones, filling only halfway up.
9. Bake for around 17 minutes or until the cakes are firm to the touch. Cool in the tins for five minutes and then gently turn out of the tins and cool on a wire rack.
10. If you want to create a piñata cake with the coins hidden inside, cut holes into two of the three smaller layers using a round pastry cutter.
MAKE THE FROSTING
11. Melt the chocolate using the double boiler method – suspend a bowl over a small pot of barely simmering water and stir until the chocolate is melted and smooth.
12. Put the mascarpone, icing sugar, chestnut purée and vanilla paste into the bowl of your stand mixer. Start mixing on low speed until the ingredients are combined.
13. Gradually add the melted chocolate and increase the speed to mix everything together. Gradually add the double cream and whisk on maximum speed until the frosting is glossy and smooth. Transfer most of the frosting to a piping bag fitted with a large round tip.
14. Add a dot of frosting on your cake stand to secure the largest cake layer. Spread a small amount of frosting over the top.
15. Add the smaller cake layer (with hole cut out) centrally over the base layer. Pipe a ring of frosting around it and sandwich with the second layer (with hole cut out). Smooth the frosting and add the coins in the cavity.
16. Pipe more frosting over the second small layer and top with the third. Smooth frosting over the sides and top of the entire cake letting the sides show through for a ‘naked’ effect.
17. Transfer any remaining frosting into a piping bag fitted with a large start tip. Pipe rosettes of frosting all around the perimeter of the base layer and around the base of the smaller cake.
MAKE THE CHOCOLATE DRIZZLE
18. Put the chopped chocolate in a small bowl. Put the cream and honey in a small saucepan and heat until small bubbles appear around the edge of the pot. Do not allow it to boil.
19. Pour over the chocolate and leave to stand for a couple of minutes. Stir until chocolate melts and add the butter staring until smooth. You can warm up in the microwave for a few seconds if it sets.
20. Add a drizzle of chocolate around the edge of the smaller cake then pipe the remaining frosting on top.
21. Serve at room temperature. Be careful when cutting so that you reveal the coins hidden inside.