My Piping Illusion cake baked with Trex

I loved creating this fun and playful take on a layered gateaux cake complete with fluffy buttercream, ganache and cherries with a magical piping bag effect.

This cake is created by using a frame inside the cake, with each layer of sponge ‘threaded’ over the tube that comes up through all layers and out of the top. The filled piping bag is then inserted into the fame using wooden skewers to support and then a final bit of buttercream is used to disguise the cake frame. Magic!

I baked the sponge with Trex which gave the sponge a really god light texture, and it’s also dairy free! If you want to be completely dairy free you can also use it in place of the butter for the buttercream, just add an extra 100g of icing sugar to help stiffen.

I thought I’d share the recipe as it’s a really fun illusion cake but not too tricky! You could change the colours of the buttercream if you wanted to or even make a chocolatey version, it’s super fun! If you do make one I’d love to see any pictures of your creations!

The Recipe and How to!

Preparation: 1 hour 30 minutes
Baking: 30-40 minutes
Serves: 25-30
Vanilla Sponge Layers:
• 750g Trex
• 750g Golden caster sugar
• 750g Self Raising flour
• 1tsp baking powder
• 15 eggs lightly beaten
• 1 tbsp Vanilla bean paste


1. Preheat the oven to 170 degrees centigrade.
2. Grease and line on the base and sides, 3 x 10” round cake tins, alternatively if you only have one tin, repeat the process until all three layers are baked.
3. Cream together the Trex sugar and paste until fluffy for a few mins with a hand whisk or in a stand mixer.
4. Add the eggs gradually beating gently until incorporated.
5. Mix the baking powder into the flour with a whisk, then gently mix in the flour until just incorporated, don’t over mix.
6. Bake for approx. 30-40 minutes until light golden and spongy, a skewer should come out clean from the centre when tested.
7. Leave to cool in the tin for 10 mins then turn out onto a rack, removing the parchment paper and cool completely.

Chocolate Ganache Filling:
• 450g dark chocolate
• 100g double cream
• 200g butter


1. Melt all together in a microwave, until amalgamated and smooth. Allow to cool until thickened slightly and at room temperature before placing into a large plastic piping bag.
• 500g room temp unsalted butter
• 2 tsp vanilla bean paste
• 1kg icing sugar


1. Beat all together until smooth, pale and really creamy, ideally with an electric hand whisk or in a stand mixer.
2. Load up into a piping bag fitted with a large open star nozzle (I used a Wilton 1M) and pipe over each layer of sponge to construct the layer cake adding a generous filling over each layer covering the ganache.
3. To decorate pipe little stars around the edge then fill in the centre with little whips of buttercream on the top of the sponge, topping each one with a fresh cherry

To create the piping bag effect, you will need:
• A clean plastic piping bag
• A large open star nozzle
• A small piece of polystyrene to wedge inside the bag
• A little off the excess buttercream
• 2 wooden skewers
• A little cling film

1. To assemble, push the long wooden sewers right through the polystyrene piece/pieces, pushing out through the front and back of the polystyrene.
2. Add the nozzle to the piping bag by cutting a hole in it and pushing in the nozzle.
3. Test the distance and length needed of the skewers. The long tips of the sewers need to be pushed right through the nozzle and extend into the opening of the illusion cake tube that extends from the cake. This will help support the weight of the piping bag once it’s filled – make adjustments accordingly.
4. Take your excess buttercream from the initial bake and pipe inside the decorative bag, around the polystyrene, do this until the bag and is full and completely masking the polystyrene inside the bag.
5. Secure the decorative piping bag at the end, and use a small piece of cling film to tie the bag up. If your skewers are showing a little coming out of the bag, this can be snipped off with strong scissors.
6. Once you’ve got your cake ready, the final step is to place your decorative piping bag into the illusion cake tube, the skewers will support the bag from falling down as there will be tension where the skewers are leaning against the illusion cake tube.
7. Use your buttercream to cover the clear plastic tube within the cake and there you have it, your cake appears as the perfect magical illusion!

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