Grease and line a 20cm cake tin and a 15cm tin - both 8cm deep. Pre-heat the oven to 180C/160C fan/gas 4. 

Make the batter for each cake in a separate bowl so you can keep the amounts correct. Beat the softened butter with the caster sugar until light and fluffy - using an electric mixer will make short work of this. 

Add the eggs one by one, beating until combined.

Gently fold in the flour, cocoa powder and chocolate chips, making sure the batter is smooth and all of the ingredients have been thoroughly mixed in.

Turn out into the cake tins and smooth the batter into place. Bake in the oven - setting the timer for about 40 minutes. The smaller cake will be ready first, the second cake about 15 minutes later - all ovens vary though so just keep checking by popping a knife into the middle of each cake. As soon as it comes out clean, the cake is ready and can be transferred in its tin to a cooling rack. Then 5-10 mins later carefully lift out of the tin and let it sit directly on the cooling rack. If you don't have much time you can pop them in the fridge to speed the process up.

While the cakes are cooling, make the frosting by beating together the butter, icing sugar, malt powder and cocoa. Keep adding a tablespoon of milk at a time until you have a super smooth frosting that'll spread easily.

Set to one side until you're ready to construct the cake.

Once the cakes are completely cool, gently take them out of their greaseproof paper and place them on a large chopping board. Trim off any lumps and bumps off the sides and top to give a smooth surface to ice.

Place the larger cake on your cake stand and then spread the top with a layer of buttercream, then stick the smaller cake dead in the centre on the top.  

To keep the cakes solidly together, poke three plastic drinking straws through the top cake into the bottom cake. Snip off the tops so they're not visible under the icing and don't forget to remove them once you start slicing later on!

You can now use half of the buttercream to liberally spread all of the visible surfaces of both cakes. Use a palette knife or whatever you find easiest. Once you've applied the first layer, smooth it around - it doesn't matter if you can still see the cake through it at this stage. Then pop the whole thing in the fridge to chill for 30 minutes.

Repeat this process again with the remaining frosting - you might not use it all but you can easily pop it in a pot and freeze it to use again in the future. Again add the top layer and then smooth and smooth and smooth it as much as you can. Chill again for another 30 - 60 mins.

Now for the fun part! Heat the cream up in a pan until it starts to bubble at the edges, then remove from the heat. Add the chopped dark chocolate and mix until you're left with a thick and glossy ganache. Allow it to cool a bit until it's body temperature - if it's too hot it'll just slide right off the cake!

If you have one, pour the ganache into a disposable piping bag, snip off the end and then pipe a layer around the top exposed edge of the cake on the bottom layer. Use the back of a teaspoon to gently encourage the drips to go down the side of the cake. Because the frosted cake has been chilled it means the drips will set more easily.

Then flood the top of the cake with ganache, and again using the back of a teaspoon push a little drop at a time over the edge to create the drip cake effect. Any leftover ganache can be chilled or frozen to use again.

Once you're happy then liberally decorate the the top with your selection of chocolate bars. Chopped up shards of curly wurly look impressive, as do contrasting white chocolate drops. Just go crazy and don't worry too much if it doesn't look perfect. I added a final dusting of edible gold stars to make it look extra special.

Pop the whole thing back in the fridge to set and then bring it out an hour or two before you're ready to serve so it softens up a bit for eating. Slice and enjoy and soak up the glory of having made the ultimate chocolate birthday cake!