This chocolate cake is a firm family favourite.  It is more like a mixture between a mouse cake and brownie than a traditional chocolate birthday cake but the flavour is amazing and everybody loves it.  The key to any birthday cake feeling like a success is down to the decorations and here you should absolutely buy what you need.  I do like most of the decorations to be edible but the best palm trees I found are were not edible. 

This cake will need to fully cool and that will take several hours so on day 1 make the cake and the buttercream and on day 2 assemble.  This cake is so moist and gorgeous that leaving it a day will not be a problem unlike lots of sponge cakes.   

Ingredients
500g white fondant Icing  
250g black fondant icing 
Bright sky blue food colouring gel (or blue fondant icing) 
12 fondant icing edible penguins 
4 palm trees 
100g soft light brown sugar 

Cake ingredients 
300g dark chocolate 
425g butter, softened 
525g light brown soft sugar 
6 eggs (room temperature) 
2½ tsp vanilla paste or extract 
210g plain flour 

Chocolate butter cream ingredients 
75g butter, softened 
150g icing sugar 
1 tsp vanilla paste or extract 
250ml double cream 
55g dark chocolate, chopped very finely

Equipment needed 
35 x 24cm rectangle cake tin 
4-6 cupcake cases 
Greaseproof or baking paper 
Cake board or glass board 

Method
Day 1 
Preheat the oven to 160c.  Line the bottom and sides of your cake tin by lightly buttering the tin and lining with greaseproof paper.   

Put a baking tray into the oven. 

Gently melt your chocolate, I do this in my microwave as I find that as long as you only do short bursts you have less chance of your chocolate seizing.  The first burst I do is 1 minute on full blast then stir using a butter knife.  After the initial burst I do 30 seconds at a time, stir and continue until the chocolate is totally melted.  Put to one side to cool very slightly.  You can do this over a ban Marie, just be incredibly careful not to get any water into the chocolate. 

Beat the butter and sugar in a stand mixer ideally until light and fluffy - this will take a couple of minutes.  If you don’t have a stand mixer you can do this with a hand whisk it will just take a little longer.  Now add 1 tbsp of flour and mix again for 10 seconds or so until fully incorporated.  Now add the eggs 1 at a time, fully mixing between eggs and scraping the bottom with a spatula every 2 eggs.  Should this mixture start to curdle (and believe me mine sometimes does), just add 1 tbsp flour and carry on.  Add the now cooled chocolate and the vanilla and mix.  Fold the flour now into the chocolate batter using a large slotted spoon scraping around the edge and through the middle, you want to keep this light so don't knock out any of the air. 

Fill 4 cupcake cases and then pour the batter into your prepared cake tin, ensuring you stay around the three quarters full mark, you do not really want to go over as it will expand and go everywhere.  Put any remaining batter into cupcake cases - these will be your boulders.  Put the cupcakes into a cupcake tray and put the cake tin on to the hot baking tray.  The cupcakes will take about 25 minutes.  Cook the large cake for 50 minutes before checking.  This cake will get a crust on the outside and fully sets on cooling but if you gently tip the tin it should not have much movement, just a very slight wobble, a skewer won't come out clean, but it should not come but with wet batter on it.  If it is not done then put back in and check every 10 minutes until done.  I expect this to take close to 1 hour 10 minutes but have known it to take a little longer.  

When the cake is cooked, leave in the tin to cool completely.  This is very soft while warm and so will break if you remove it prematurely from the tin.  Once cool the crust will sink back a little and a few chunks may well come off, if that happens just be the hero and check it tastes nice, I find it is better if you taste it with the buttercream- just to be sure it tastes ok.  Remember, not all heroes wear capes.   

While your cake is cooling make your buttercream.  Put your cream into a small saucepan and heat until it just starts to boil.  Put the finely chopped chocolate into a heat proof bowl and when the cream boils, tip the cream over the chocolate.  Stir once and then leave for a full minute before stirring until smooth and glossy.  Put to one side for at least 15 minutes. 

When the chocolate is cool beat the butter and vanilla in a stand mixer for 2 minutes until super light and fluffy.  Slowly start to add the icing sugar with your mixer on slow at first because otherwise trust me, your kitchen will be covered in icing sugar. Once all of your icing sugar has been added increase the speed, the mix will be fairly stiff.  Stop the mixer and add your now cool chocolate.  Turn the mixer back on, on medium and beat until fully incorporated.  Put into the fridge overnight to set.

When your cake is completely cold cover the whole cake in the tin in cling film and put to one side. 

Day 2 
Take your buttercream out of the fridge and leave to one side for an hour.  Put your buttercream back into the mixer and mix until light and fluffy again. 

Take your cake or glass board and put a spoonful of buttercream on it. 

Remove the cake from the cling film and tin and place on the glass board upside down so that the crusty part is at the bottom and the top is perfectly smooth. 

You now need to put the buttercream over the top and sides of the cake as this is effectively your glue to get your sand and icing to stick nicely to the sides of your cake.  Put 2 large spoonful's of the buttercream on the top of the cake and with a palette knife ideally (but a butter knife will also work), spread the buttercream over the top of your cake keeping it as even as possible.  This does not need to be thick at all but does need to be even as this will affect your finished look.  Don't worry if it dribbles down the sides as you will also be covering the sides with buttercream. 

Now the top is done, you need to cover the sides.  This is the part I used to really struggle with, much easier if you know how to plaster a wall.  However, it is doable and you will get better with practice.  With your knife carefully start to paint the outside, here I would say that although you don't want to waste buttercream, if you are a little heavy handed don't worry too much because effectively what you will do is with your palette knife, scrape off the excess.  How you do this is hold you palette knife vertically against your cake and go around the edge removing any excess buttercream, scraping it into a spare bowl.  Repeat with the top of the cake.  You don't want too much buttercream because I find it makes the fondant icing too soft and sensitive so that thumb prints are more likely.  You want just enough to stick the icing and for me, it is easier to do the excess and scrape than try to be perfect first time.   

Take 4 or 5 of your cupcakes and cover these with buttercream as best you can - these will be fiddly so just do your best.  I like them to be different sizes so maybe cut one down a little so it is smaller and with buttercream 'glue' this to another. 

Remove any crumbs from your work surface, clean down and thoroughly dry.  Remove any rings or bracelets you are wearing.  You need to roll out the fondant icing and moisture, crumbs and jewellery are the enemy of fondant icing.  Take cornflour and dust your work surface fairly liberally.  Cut open your white fondant icing and cut off ¼ of it and cover in the packet. 

We are starting with the sea so you need the larger piece of white fondant.  Knead the icing for a minute or so until it is soft and pliable.  Now dip a knife into the blue food colouring and wipe it on the white icing.  What you are going to do now is to knead the icing so the icing goes blueish but don't mix thoroughly, the mottled effect will give your sea the effect of movement.   

Redust your worksurface and your rolling pin with cornflour.  I find that the fondant can stick once you start to roll it out despite the flour, so turn the icing one turn to the left every few rolls and be aware you may need to add more cornflour underneath if it starts to feel too sticky.  Roll until the icing is large enough to cover half of your cake and ideally the thickness of a £1 coin as it is then less likely to break.  Fondant icing can be a bit of a pain and stretches and cracks fairly easily so try to handle it with care and try not to make it thinner than a £1 coin, a little thicker is ok. You want the sea edge to not be dead straight as it is supposed to be the sea lapping up the shore. 

Once you are happy it is large enough and the right thickness the easiest way to move it from the board to your cake is to gently and carefully roll the icing around the rolling pin.  Before you start move your cake back to your work area close to the icing so you can move quickly.  Lightly dust cornflour over the top of your icing and smooth it over - this removes any excess - and very carefully, starting on one edge (I tend to work left to right but if you are left handed you will probably want to do this right to left), gently roll the icing around the rolling pin, wrapping it over itself.  

Move the rolling pin so the icing is above your somewhere around the middle and gently unroll the icing over your cake - this does need to be centralised so that it will cover down the sides all the way to the bottom.  Once the icing is over the cake you will not be able to move it because it will stick to the buttercream.  

Firmly and carefully glide your hand or smoother over the top and then around the side of the cake over the icing.  I do sometimes find that the fondant around the top edge cracks slightly, I have no idea why but do know that if I gently hold my hot hand against it for 5-10 seconds then with my finger I can carefully smooth it and it does somewhat diminish.  I like to use my hands to push the bottom of the icing a little to ensure it is against the cake.  Then take a small knife and cut around the edge of the icing at the bottom of the cake, try not to cut it too short.  

The thing to say here is that you really do not want your fondant icing to dry out while you are working with it so from the moment you open the packets to the time you fit it to the cake, do this in one sitting rather than leaving the icing for any length of time. 

Turn now to your boulders - the buttercream covered cupcakes. 

Take the black icing and your remaining white fondant.  Knead both separately initially for a minute or so until they are soft and pliable.  Now you want to semi mix them together so that your boulders have a mottled effect.  Put both coloured icing together and just knead together until the colour is more black and grey than white and grey, keeping them not fully mixed. 

Redust your worksurface and your rolling pin with cornflour and roll until the icing is the thickness of a £1 coin.  Cover each of your cupcakes with the mottled grey icing and place on your cake. 

Take your palm trees and carefully place these around the back of the cake, away from your sea and behind your boulders. 

Take the soft light brown sugar and thoroughly coat the exposed part of the cake with the sugar, this is your sand for your beach.  Just use your hands to gently push the sugar into the buttercream - especially around the sides.  Ensure all of the buttercream is generously covered. 

Place your penguins and you are done.