Octonauts birthday cake- Kwazii and Gup-B

As the Octonauts have inadvertently crept into our lives and my 3-year-old is an utter fan, verging on obsessed, baking an Octonauts birthday cake was perhaps the best surprise present he could get.

Which Octonaut for a cake?

When it came to planning Max’s birthday there was no real question about the theme: it had to be Octonauts! However, the difficulty was choosing the exact subject for a birthday cake, which of his favourites would be the best for a birthday cake?

Captain Barnacles, the brave polar bear captain?  He’s a real hero who can drive any ship or Gup, and is strong enough to lift even giant clams.

Or should it be Kwazii, the cheeky cat with a mysterious pirate past?  He fears almost nothing (except spiders) and speeds like daredevil in Gup B.

Maybe Peso, the medic? This penguin always overcomes fear to help others hurt or in trouble.

In the end Kwazii won.  The cheeky pirate and his speedy Gup-B were to have the starring role on my little birthday boy’s table.

With the theme set, it was time to get baking a special home-made Kwazii birthday cake for him!

The base of our home-made cake

I made two Genoese sponges.  (Here’s my video of making a basic sponge cake )

I like the Genoese sponge because it’s easy to make, it’s light and dairy-free. However,  you can easily use other recipes, or even go-to ready mixes.  I love Wright’s cake mixes, for example, (the chocolate fudge cake mix in particular) for their reliability and great taste.

Once the sponges had cooled we set about spreading the filling and carving the submarine shape. (I say we, because I tend to make birthday cakes with my friend Jennie, as we work really well together, complimenting each other’s skills well)

Creating the shape of Kwazii’s submarine as a cake

As a model, we found a picture of Kwazii’s Gup B to model what we wanted the cake to look like and then started carving away. 

This process needs a sharp serrated-edged knife to ensure nice clean edges. 

Draw on the cake, with food colouring, the basic shape you achieve and then carve away a little at a time

Note: The leftovers are great to have with tea or milk or to make bread and butter pudding from.

Our shape soon started to emerge- even without the icing, it was looking like Gup-B.

Max had asked for a strawberry cake, but instead of flavouring the cake, we added strawberry jam to the buttercream (which was actually made from non-dairy butter).

In the same way you can add other flavours or simply use jam or a a chocolate spread. Your imagination is really the limit in what flavour you want. Just make sure that the filling is the right consistency, not too runny or won’t soak your cake mixture.

The Gup B vessel was relatively small (enough for a party with 8-10 kids, but we were also catering for 8-10 adults), so we stood the carved cake onto another flat layer of cake. This was first cover with a blue-coloured white chocolate, that I melted, poured, smoothed over and let go hard, before placing the Gup B on it.  This was our sea.

Fondant icing for the cake

Fondant icing really does give a cake a much more professional looking finish.

Our previous cakes have taught us that shop-bought icing, often from Aldi, is the easiest and most time-efficient to work with. Though using marshmallow fondant, as we did on the Princess Castle Birthday cake, does hide more unevenness.

While Jennie carved away at the surprise cake, I started to colour the shop-bought fondant icing. 

This was quite a time-consuming and messy process.  We added colour little by little, layering it, adding more red, green, blue, as they blended. Finally, we got the colour we wanted: the orangy brown of the Gup B.

Along the way, we’ve learnt that it’s important to use good quality colouring paste to colour fondant, otherwise it becomes runny and sticky, impossible to work with. We use Sugar flare colouring paste which we bought on Amazon

Covering our home-made cake with the fondant icing

The next step was to roll the icing out and cover the cake. 

Since our first cake- the Lightning McQueen cake– we’ve learned a trick or two:

• Fondant icing rolls out much better when it’s been kneaded for a while and has warmed through
• Using a silicon baking mat (or greaseproof paper if you don’t have silicon) scattered with thin layer of icing/powdered sugar works
• On top of the fondant we’ve started using cling film to stop the fondant icing sticking to the rolling pin.

Once we were satisfied with the shape, we used strawberries and our cream cheese mix inside too.

We covered the cake in a thin layer of buttercream.

Then gently draped the rolled out fondant icing over the cake.

Here comes the delicate part of working the fondant gently around the cake and tucking it under. You have to make sure not to stretch it and work relatively fast, but gently as the fondant can crack. (as it did for us).

Once the cake was covered, the seating area cut out,  the teeth added, it was time to put the cake in the fridge overnight. (Jennie said goodnight at this point and I carried on)

Kwazii figure from marzipan

I made Kwazii, the fins and the tail part of Gup-B from marzipan.  I bought a large pack of white marzipan from the shop and coloured that to my needs.  As I had bits and pieces left over I also made some fish and starfish, which I sprinkled with a hint of edible holographic glitter.

Kwazzi took me about an hour to make out of marzipan.  Both he and the other marzipan pieces needed to go into the fridge as soon as possible, so they’d harden up.

Top tip: if you don’t feel you have the time or the skills to make the figures yourself, just buy a good quality figurine (or use an existing toy, washed very well). Your child will probably appreciate the extra little present to play with.

The fins and tail had a couple of toothpicks inserted in them, sticking half out to be inserted on to the cake later.

Finishing touches to our home-made Octonauts cake

Just before the party I assembled everything;

I made up some blue jelly/ jello- this was to be the sea around the Gup-B.

• The fins and tail were attached to the Gup B with the help of the toothpicks
• I scooped the jelly around the Gup B, scattered blueberries through it (one of Max’s favourite fruits) to create a wobbly seabed
• and embellished the sea bed further with marzipan fish and clams I’d made and candy strings.

Our Octonauts birthday cake was an utter success!  The flavours worked really well together and Max was overjoyed seeing his favourite Octonaut, Kwazii.

Which is your little one’s favourite Octonaut?

If you end up making an Octonauts birthday cake yourself, please share with us on Instagram or Facebook. We’d love to see your cake!