Bottle Rocket Cake

Bottle Rocket Cake

Given my son is now 4, this is a bit of a belated post. However, given the effort I placed into this cake at the time, I felt the need to blog it to not only keep a record of the experience before I forgot how I achieved this insane cake but also to share to the internet world that seemingly impossible feats are possible if you try really hard. I apologise for the note like explanantions, I wrote this post in a flash. If you are keen to challenge yourself and give this bottle rocket cake a go I am more than happy to answer any questions you have or update the post to explain things a bit better, just let me know.

So it was my son’s third birthday and we had been playing and experimenting with bottle rockets over various mornings and afternoons for the previous few months. It should have come as no surprise that he requested a bottle rocket cake when I asked him what type of cake he wanted for his birthday. Given that I made an epic watermelon cake for his second birthday, he gave me the look of expected compliance to his somewhat rediculous request. Of course, feeling up to the challenge, I decided to give it a go and the following documents the rediculous bottle rocket cake that ensued.

Bottle Rocket
Bottle Rocket

A lot of planning went into the making of this cake. I even had a notebook where I splurged my ideas and recipes for how I was going to achieve each component of the cake to make it look like a bottle rocket. I desparately wanted it to not only look amazing but also taste amazing. However, I had to caution myself against going too far and decided that the stand (what holds the cake upright and) did not need to be edible and convinced myself that using a piece of PVC pipe wrapped in foil would be good enough. I considered using pink wafers or fondant for the fins to limit the amount of chocolate in the cake overall but then I realised that I needed the fins to help stabilise and hold the cake up when it was assembled so settled with white chocolate. I had intended to use blue fondant to make a blue bottle cap to matched the sprite bottle cap we used on the real bottle rocket. I ran out of time on the day to create it, which is why it features in the planned design but is not present on the actual cake.

Bottle Rocket Cake Design Notes
Bottle Rocket Cake Design Notes

Chocolate Tempering

The aim was to make a bottle rocket cake that looked similar to the actual bottle rocket we had built. This meant parts of an L&P bottle, Sprite bottle and core flute was to be replicated, well represented in cake and chocolate form. I even went to the effort to use dark chocolate to represent the water fill inside of the bottle rocket whilst the rest of the main bottle rocket shell is made using milk chocolate to give the contrast. When I made the bottle shells using tempered chocolate, I was really anxious and worried that it would not hold or it would not be strong enough and break when I filled it or whilst I assembled it. As a result i made the shell too thick, it ended up being about 5mm thick when really 2-3mm would have been enough. My thought process was that it was better to go thicker to ensure it holds as I only had one chance to pull it off.


The bottle rocket cake is filled with alternating layers of chocolate mud cake, plain sponge, buttercream, raspberry jelly and fizzy chocolate discs. I used store bought chocolate mud cake and sponge cake to save time as i am only one person trying to pull off this ridiculous cake. However, go ahead and make your own if you prefer or have the time to. Of course you could use a store bought cake mix to ensure freshness or your own recipe. I feel the cake part of the layers on its own is not something that needs to be opulently decadent on its own; it is the combination of all the components of this bottle rocket cake that makes this cake opulent. In saying that, a standard chocolate cake or chocolate sponge would work as substitutes for the chocolate mud cake. Similarly, vanilla cake could be used in place of plain sponge.

When I made the raspberry jelly, I did not bother to strain the seeds out of the mixture before adding the gelatine again because of time and because i personally do not mind a few seeds in my raspberry jelly. Although, it would increase opulent level factor if you did strain the seeds first. Fancy!

Bottle Rocket Cake Cut
Bottle Rocket Cake Cut

Try to be strategic with the placement of the buttercream and the cake layers when layering. It is best for presentation purposes to avoid air gaps in the cake (nothing worse than cutting into a cake and serving a piece of cake full of stuff and then another piece full of pockets of air, that just would not be fair!). When I layered the layers, I used the buttercream to filled the gaps, particularly between the chocolate bottle shell and the fillings. Similarly, with the chocolate cake and sponge cake it was easy to use scrap pieces like gap filler and ensure a complete layer of cake. Be mindful that the chocolate fizzy discs and raspberry jelly do not have the same flexibility during assembly so try to alternate them with layers that do to hide the gaps.

The big day

On the day, wonder and amazement was provided at the party on the cake reveal. Unfortunately, I accidentally dropped the green bottle shell when I was trying to assemble the cake and it broke. I was sad, but my sorrow did not last long, as soon as I tasted the layers of cake together in one bite I was proud of the creation and the joy on my son’s face was worth it – I like to think he is proud to have a mum that likes to challenge herself too. Anyway, onto the ridiculous cake!

Bottle Rocket Cake

Serves 16


Chocolate to form bottle

160g Dark chocolate

490g Milk chocolate

200g Green chocolate or green candy melts

200g white chocolate

Chocolate Fizzy Discs

3 tbsp sherbet

190g milk chocolate

Raspberry Jelly

200g raspberries

1 tbsp caster sugar

2 sheets gelatine

Vanilla Buttercream

3 cups icing sugar

1/3 cup unsalted butter

1 1/2 tsp Vanilla essence

1-2 tbsp milk

Store bought chocolate mud cake

Store bought plain sponge cake


Chocolate bottle shells and fins:

Remove the label form a 2L L&P bottle. Set aside.

Draw a line 1/3 up the bottle when upside down.

Cut the bottle in half in the middle of where the label usually sits.

Melt and temper dark chocolate.

Coat inside of the top of the bottle up to the marked line.

Allow dark chocolate to set a little, then quickly invert. Tidy with a spatula if required.

Melt and temper milk chocolate.

Coat the remainder of the top of the bottle using milk chocolate. Invert and allow to set.

Once set, use a craft knife to cut the plastic bottle and remove the plastic bottle away from the chocolate bottle shell.

Coat inside of the bottom of the L&P bottle using milk chocolate. Place upside down to set.

Like before, once set, use a craft knife to cut the plastic bottle and remove the plastic bottle away from the chocolate bottle shell.

Cut top off 2L Sprite bottle.

Temper green chocolate or melt green candy melts if using.

Pour into bottle top and coat well. Wait a minute then invert to set.

Again, once set, use a craft knife to cut the plastic bottle and remove the plastic bottle away from the chocolate bottle shell.

Melt and temper white chocolate.

Spread onto a cold baking sheet to create a flat sheet of chocolate about 5mm thick.

When set, use a hot knife to cut triangle shaped ‘fins’ for the bottom of the bottle rocket.

Chocolate Fizzy Discs

Melt chocolate, stir in sherbet.

Squash it flat between 2 sheets of baking paper.

Once set, cut circles similar to the diameter of the bottle.

Use a warmed cutter to melt through the chocolate.

Raspberry Jelly

Soak gelatine in cold water for 5-10 minutes

In a saucepan, combine raspberries and sugar. Bring to the boil then take off the heat.

Squeeze gelatine with your hands then add to raspberry mixture.

Whisk until dissolved.

Pour onto a baking tray; place in the fridge to set.

Once set cut circles similar in diameter to that of the bottle.

Chocolate mud cake

Remove any icing on the cake and cut circles of cake out that are similar in diameter to that of the bottle.

Sponge cake

Cut circles of cake out that are similar in diameter to that of the bottle.


Fill brown (milk/dark chocolate) bottle shell by alternating layers of chocolate mud cake, raspberry jelly, sponge cake, vanilla buttercream and fizzy chocolate discs. Make sure to press firmly but gently after placement of each layer to ensure the bottle rocket will be filled.

Place foil wrapped PVC pipe in centre of a cake board and place the filled bottle, neck side down into it.

Get the L&P label and re wrap it around the bottle using some buttercream to stick it into place.

Melt some white chocolate and use it to “glue” the fins onto the sides of the bottle rocket cake near the bottom of the structure.

Place green bottle rocket on top with neck of “bottle” pointing upwards.

Cut the cake using a warmed knife and slicing length ways across the bottle rocket to ensure each serving showcases the layers.

All done and enjoy!

Mel Crafting.

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