Rainbow alphabet block cake

IMG_7762-2My son turned one the other day (eeeek! How time flies). I couldn’t wait to make his first birthday cake with my Thermomix! It was just a small family affair so no party theme, but I still wanted to make something cute… he loves playing with his wooden blocks so decided on an alphabet block cake.

I’m no cake decorator. Actually, this was my first cake decorating project. When it came down to the wire, I was wondering how on earth was I going to pull this off?! Stay positive – you got this, I told myself.

So I made the fondant first. Marshmallow fondant. I hunted for vegan, white marshmallows. No joy. I then hunted for plain white marshmallows. No joy. So in the end I had to buy the Pascalls mixed pink and white mallows.

Marshmallow fondant

I used Tenina’s recipe:


500g marshmallows (not homemade, sorry folks!)

2 tbp water

500g icing sugar plus some extra

Vanilla or other flavoured essence to taste

2-3 tbsp cornflour


Place marshmallows and water into Thermomix bowl and cook for 6 min/70º/speed 2.

Add icing sugar, vanilla and cornflour and mix for 10 sec/speed 6.

Knead for 2 min/Interval.

I made the fondant a couple days before and kept it in a container on the bench. I chose to use a marshmallow fondant because I don’t really like the taste of ordinary fondant.

Rainbow cake

I used ThermoVixen’s recipe:



130G Butter (Room temp)

80g Extra Virgin Olive Oil

250g Caster Sugar (You can use raw sugar and break it down to caster sugar as step 1.)

1tsp Vanilla Bean Paste

2 Whole Eggs

3 Egg Yolks

250g Self Raising Flour (I used cake flour)

130g Butter Milk

1/2 tsp Baking Powder


  1. Add the Butterfly to the TM bowl. Add butter, sugar, olive oil and vanilla paste to the bowl. Begin mixing on speed 4 until the mixture becomes a light, fluffy consistency.
  2. When you are happy with the look of the batter (usually between 1 minute and 1.5 minutes) reduce speed to speed 3. Whilst still mixing add the eggs through the hole. Add each egg separately give it about 15 seconds each time to thoroughly mix. Add each of the Yolks the same way. This should take about 3 minutes for the whole process. (step 1 and 2)
  3. Stop the mix and scrape edges. If you are happy that it is all combined add HALF of the flour, baking powder and butter milk to the bowl. Mix on speed 3 for 30 Seconds.
  4. Again scrape the edges of the bowl and add the remaining flour, baking powder and butter milk. Mix on speed 3 for 30 seconds. You can give it a further 10 seconds on speed 4 to ensure it is all mixed through thoroughly.

From here, I split the mix between two bowls. I then stirred in some colour: Hopper’s Natural Colours (bought from Loose Produce in Como). The colours are derived from fruit, veggies and plants. You can find Queens branded “natural” food colourings in Coles/Woolworths, but if you read the label, some of the colours contain cochineal extract. This just grosses me out as it’s actually crushed insects.

I did have a go at making my own dye but I ran out of colours! (I juiced some beetroot in the Thermie which was fantastic and did the same with spinach and carrot, but the carrot went a bit brown after a while so wasn’t sure if it would work too well).

5. Mix some colour into your batters and then pour into square baking tins.

6. Bake for 20 – 25 minutes at 180 degrees. You will need to test the cake and make sure that the skewer comes out clean. It should move away from the edges slightly.

Repeat twice to get your 6 layers.

I wrapped each layer in cling wrap and put them in the freezer.

Buttercream icing

I followed the buttercream icing recipe found in the Everyday Cookbook (EDC). This was used to prevent the filling from seeping out and to cover each side of the block. I used about 4 batches.


I alternated the layers with strawberry jam and whipped cream.

Strawberry jam

I used Quirky Cooking’s 8-minute jam recipe (but used raw sugar instead of rapadura as hubby didn’t like the rapadura version)

1.  Before you begin, place a saucer into the freezer for testing the jam on.  Wash out your jam jars thoroughly with warm soapy water and rinse well.  Set aside.

2.  Place fruit in Thermomix bowl and chop roughly on speed 4 for 3-5 seconds, depending how chunky you want it:
– 500g strawberries (or other fruit)

3.  Add and cook 8 minutes, 100 degrees, reverse, speed 2:
– 150g Rapadura (or other sweetener)
– 1 level teaspoon agar-agar powder
(If you prefer your jam smooth and un-chunky, cook without the reverse, and puree on speed 8 when you’re done.)

4.  Test if the jam is set by placing 1/2 tsp of jam onto the cold saucer.  When it is cool, push it with your finger.  If the jam wrinkles, it’s ready.  If not, add a pinch more agar-agar, cook for another 2 minutes, then re-test.

5.  When jam is set, pour into 2 hot rinsed jars with twist-off lids and close immediately.  Turn jars upside down for 10 minutes.  Your jam will keep in the fridge for up to one month.

Assembling the cake

1. Divide the fondant by the number of colours you’ll be using for the letters. You’ll need to heat each ball of fondant for about 25-20 seconds in the microwave  just to soften it first. Knead in your colour and then roll each ball with a rolling pin (2-3mm thick). I oiled the pin with some coconut oil to prevent the fondant from sticking. (My wonderful husband helped me with the fondant and assembly – team effort!)

2. Grab your cake layers from the freezer and stack them up so you can determine how long your strips need to be for each edge of the block face. Cut them using a sharp knife (about 2cm wide).

3. Figure out what letters you’d like to use and cut those out too. We used C-A-L-E-B to spell out our boy’s name.

4. Next, fill a piping bag with buttercream icing and pipe around the edge of the first cake layer. It need not be too thick, just enough to hold the filling in. Spread strawberry jam on the rest of the cake layer.

5. Pop the next cake layer on top of your base layer and repeat the buttercream piping. This time, spread whipped cream on the layer. (Follow recipe in EDC – I didn’t add any sweetener as the cake is sweet enough). Alternate between jam and cream until you’ve done all layers (except the top layer of course as this will have buttercream only).

6. Using an icing spatula, spread buttercream onto each side of the block. Try to get it as smooth as possible.

7. Position the fondant strips around each side of the block. Cut each end at a 45 degree angle, ensuring the edges that meet sit snug.

8. Lastly, position the letters on each side of the block.

And then you’re done!

2 thoughts on “Rainbow alphabet block cake

    • Thank you Tenina 🙂 What a lovely name our sons share! Sounds like he’s got a fantastic adventure ahead of him.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s