Posted in Baking Day

Prince William’s Chocolate Biscuit Cake

Prince William & Catherine Chocolate Biscuit Cake
It’s official, the happy Royal couple HRH Prince William & HRH The Duchess of Cambridge – Catherine are officially married and it’s time for them to cut the cake.  As per my previous post, I’ve used the Chocolate Biscuit Cake recipe from the Royal Chef website and here I’ve converted the measurements to metric.  I made the biscuit base yesterday evening and left it to set in the fridge overnight.  This morning I opted to add a ‘secret’ ingredient and melted 5 Mars bars with a little water and spread it over the top.  After letting this firm up in the fridge for an hour, I then poured over 3 melted Galaxy milk chocolate bars.  I then happily snapped Cadbury’s Chocolate Fingers in half and lined them around the cake.
Prince William & Catherine Chocolate Biscuit Cake - a slice
Verdict – sublime.
The Royal Chef instructed to use a 6 inch by 2.5 cake ring however I chose to use a much wider ring of 23cm to make a wider, flatter cake, as I knew it was going to be extremely rich and a little sliver would go a long way.
William & Catherine Chocolate Biscuit Cake up close
You will need (for the cake):
110g dark chocolate (I used 70% Lindt)
110g caster sugar
110g unsalted butter (softened)
1 egg
225g McVitie’s Rich Tea biscuits
Cake ring – springform release preferably.
Line a baking tray with some parchment paper.
Place the cake ring on the parchment paper – you are not using a cake tin, just the ring of a cake tin with base removed to shape the cake.
Beat the unsalted butter until smooth and then beat in the caster sugar.
In a separate bowl break the biscuits into almond sized pieces.
Melt the dark chocolate and gradually beat it into the butter mixture until smooth.
Lightly beat the egg and then mix this into the butter mixture.
Add in the broken biscuits and stir well to cover with the cake mix.
Spoon the chocolate biscuit mix into the cake ring and press it down and out to the sides with the back of the spoon.
Place the cake in the fridge to set overnight.
You will need (for the topping):
5 x 58g Mars bars
3 x 125g Smooth Milk Galaxy Chocolate bars
1 x 125g box Cadbury’s Chocolate Fingers.
A little water
Remove the ring from the cake and turn the biscuit cake upside down (as the bottom is smoother – this will now be the top) and place it on a wire cake rack. (Put some parchment paper underneath to catch dripping melted mars & chocolate!)
Cut the Mars bars into small pieces and melt them in a saucepan with a couple of tbsps of water – mixing well to form a smooth topping.
Pour the melted Mars topping onto the biscuit cake and chill it for an hour.
Break the Galaxy Milk Chocolate bars into small pieces and melt them with a little splash of water, mixing well to form a smooth, thick, chocolatey sauce.
Pour the melted chocolate over the chilled Mars topped biscuit cake and then carefully move the cake from the wire rack onto a cake display/plate.
Cut the Cadbury’s Chocolate Fingers in two and line them around the side of the cake – pressing them into the melted chocolate to fix them in place.
Again chill the cake until the chocolate topping has set and then serve.
(If you wish to pipe something on top, as per the pictures, mix together some melted dark chocolate and icing sugar to form a firm paste that will hold it’s shape when piped.)
Til next time, Sheila


Irish Author - Dubut romantic fiction novel 'Good Enough' published in 2021. 'Gimme Dinner' a collection of 50 great dinner recipes published in 2022. 'Enjoy' published by Mercier Press in 2016 .'Gimme the Recipe' published in 2012. Work in admin of our Food Safety Consultancy business - Industrial Management Systems with my husband Denis.

36 thoughts on “Prince William’s Chocolate Biscuit Cake

  1. please, please, please make that for me when i come home….looks dlish – loving the inspriational topping!!!

  2. Please tell me what is “caster sugar” and are those “tea biscuits” sold at the store? Sorry I am from South Ameria and are not familiar with those two items.

    Thank you,


    1. Hi Kathy,
      Caster sugar is a finer ground sugar than regular granulated sugar so you can just use ordinary sugar instead. Rich Tea Biscuits are a plain, sweet biscuit similar to a Marie biscuit. If you look it up on Wikepedia you’ll get an idea of what you could substitute it with or use some type of plain cookie that you like. Enjoy 🙂 Sheila

  3. This sounds really good and rich. You said that you converted the recipe to metric. Can you give me the measures in standard ounces and pounds. I would really appreciate it. Thanks-Sharon

    1. Hi Sharon – thanks for your comment/query. The original recipe for the biscuit cake base is from the ‘Royal Chef’ website. The imperial measurements for the biscuit cake base are 4 ounces dark chocolate, 4 ounces sugar, 4 ounces unsalted butter, 1 egg and 8 ounces Rich tea biscuits. Enjoy.

  4. If you cannot find Mars bars in US use Snickers. Use any short bread cookie. Be sure guests are not allergic to peanuts.

    1. Thanks for the suggestions Joyce. The Rich Tea biscuits are a lot less buttery than shortbread but any biscuit that you like will work.

    2. The US equivalent of English Mars Bars are US Milky Way Bars – not Snickers which contain Peanuts.

      I know because I used to make both of them.

      Also, the most likely biscuit used for Prince William’s cake are McVities Chocolate coated digestive biscuits. An English favorite.
      They come in Milk or Dark chocolate types.
      I think the Dark would be best though either would work.

      1. Thanks Bill. What we call Milky Way bars has no caramel topping but having googled the US version I can concur that the US Milky Way is the same as the European Mars Bar!

  5. I’m concerned about the egg seeing as it’s not cooked. Would it work as well without the egg.

    1. Hi Christine. I had reservations too about using the raw egg but as I wanted to stay true to the Royal Chef recipe I went ahead and used it. As the cake is refrigerated and kept cold there is limited opportunity for bacteria to grow however it should work perfectly fine without the egg too as there is enough melted chocolate to keep everything bound together. Enjoy, Sheila.

  6. I made this cake and took it to a party of ten – everyone had a piece and loved it – no left overs!!! Will definitely be making it again, very easy to make and sooooo good!

  7. i want to make for wedding how long before can i make cake with no egg will be using brandy and baileys

    1. Hi Maureen. Good idea not to use the egg if you are going to make the biscuit cake ahead of time. Once the biscuits have been well coated with the chocolate, brandy and bailey’s mixture I would imagine that once it cools and hardens if you were to wrap it up well in greaseproof paper it should keep well for a week anyway. This is just my guesstimate though as I’ve never made it that far in advance so I would suggest that you make a sample one and see how it holds up. I would hold off on topping it with the melted mars and melted galaxy until a day or two before you need it. Would love to know how it works out and how far in advance you make it. Best wishes, Sheila.

  8. I have one in the fridge setting I have been looking for the recipe that used egg for ages I remember this from primary school in Ireland a friends mum made it and dispite asking people over the years I only ever got very vague instructions fingers crossed this one turns out how I remember it the egg changes the taste from the golden syrup versions thanks x

  9. Made this cake at the weekend for my sons confirmation – it was fantastic. used double quantity to make a large one

      1. That’s great to hear! I’ve adapted it as our Christmas cake for the past couple of years. I don’t use egg – doesn’t make a difference and I use melted white chocolate and then decorate with white choc fingers around the edges & snowball type sweets… goes down well

  10. I personally love chocolate biscuit cake and this is a brilliant recipe but would you by any chance have a chocolate biscuit recipe without raw egg?

    1. Hi Caroline, as this was based on the original Royal Chef chocolate biscuit cake that is why raw egg is included. Once the cake is kept sufficiently chilled and not left out for prolonged periods it should be perfectly safe however leaving out the egg will worktoo as long as there is enough chocolate to bind the biscuits and it will be just as delicious. Enjoy, Sheila.

  11. I have been asked to make a biscuit wedding cake for my niece. the K&W cake looks great but I would need it to be appx. 3″ in depth do you think I could use the biscuit as a base then put a chocolate sponge on the top & then ice & decorate it? I would appreciate your comments.

    1. Hi Mea, hmmmmm I don’t know about putting sponge on top of chocolate biscuit cake. I would suggest that you experiment with that on a small scale first to see how the combination would work out. The easiest thing to do would be to make two or three chocolate biscuit cakes and stack them one on top of the other with a layer of melted chocolate in between. You could vary each layer with different surprises i.e. using white chocolate on one layer, maybe crushing in some malteessers in another layer or maybe your niece’s favourite chocolate on one layer and the groom’s on another. Good luck! 🙂

  12. This is a wonderful treat – I added a chopped Toblerone bar to the cookie mixture – adds a wonderful surprise. (you can also use a Skor bar instead of the Toblerone). Absolute decadence and yet simple to make.

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