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Bubbling Cauldron Halloween Cake

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Bubbling Cauldron Halloween Cake! Um, have you ever seen a bubbling cauldron that’s also a cake? I mean, I think I might’ve outdone myself with this one. For those of you who know me well, you know I’m not a fan of fondant and for the longest time I had a very strict no-fondant rule. Well, I broke it! I’m tired of saying no to things, I want to start saying yes, a lot more. So, I decided to use fondant to make the tentacles. And believe it or not, they’re very easy to make!

Bubbling Cauldron Cake

Nicks favorite thing…

I adore how cool this cake is. There are two things I love. Those Ursula-purple tentacles. Heck, let’s say those are her tentacles. And the bubbles that come out of this cake. This cake is so much fun to make and it’s one of those cakes people look at and say, that’s so cool, I want to make that. It’s by no means a quick cake to make, it takes a couple days of planning before you put it together but it’s so worth the effort!

Close up of Bubbling Cauldron Cake

What does it taste like?

This cake is made of my vanilla cake recipe with is moist and delicious and is flavored with lime flavoring, which you can definitely replace with fresh lime zest. The fondant is fondant. It’s edible, but unless you’re a mega-fan, you’re not eating it. The frosting is chocolate flavored American buttercream frosting.

What are the ingredients I need?

All-purpose flour – also known as plain flour.

Caster sugar – also known as superfine sugar.

Salt – I used fine salt.

Unsalted butter – You can use salted butter. Just leave out the salt in the cake recope. And make sure your butter is softened.

Eggs – I used large eggs.

Milk – I used cow’s milk but almond or oat milk will work.

Vegetable oil – you can also use sunflower oil instead.

Yogurt – The Greek yogurt helps ake the cake moist. You won’t be able to taste it. Alternatively, you can use sour cream.

Vanilla ExtractAlways use good quality vanilla extract when baking, it makes a huge difference. I have a great recipe here for it if you’d like to try your own!

Lime flavoring – The brand I used is ‘Roberts’. Alternatively you can use lime zest.

Food gel coloring – I used chefmaster food gel.

Chocolate American Buttercream Frosting I have a really great recipe for this that you can grab here! It’s great for cupcake, cakes and buttercream decorations!

Fondant – The fondant brand I used in this recipe was ‘Satin Ice’. I bought mine from a store in Australia called Spotlight. Any brand will do. The best way to color it is using food gel and not liquid food dye.

Using Dry Ice

Where did I get it?

Ok, so a couple notes about the dry ice. I bought mine from a place in australia called BOC Gas Australia. I believe in America you can get it more easily than here.

Using it on this cake

You want to make sure that the dry ice is used in a bowl which is place in the cake. Not using the bowl will result in a disaster. Technically you’re not supposed to eat it and without the cake it will soak into the cake and make it soggy.

When should I use it?

Make sure you wear gloves when using it and don’t let it touch your skin. Make sure you add it right before serving. The bubbling only lasts for a out 20 seconds when mixed with water.

Equipment I used

  • Oval shaped cookie cutters
  • 8-inch half sphere cake tin
  • X2 8” round cake tins
  • Large mixing bowl
  • Large serrated knife
  • Electric hand mixer
  • Cake leveller
  • Spatula
  • Small offset spatula
  • Large piping bags
  • X2 8” cake boards
  • 6” cake board
  • 5inch round cookie cutter
  • Small ball shaped fondant tool
  • Plastic wrap
  • Different size round tips
  • Bubble straws
  • Fondant roller
  • Toothpicks
  • Oval cookie cutters

My Top Tips!

  • Make sure you wear gloves when adding the dry ice to the bowl.
  • Make sure you plan ahead when making this cake! It’s all about prepping ahead of time to make sure everything works.
  • Make the fondant pieces first. Especially the tentacles. They need a couple days to set before being used.

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I hope you guys enjoyed this simple but delicious recipe with me. Please comment in the comments section below, or feel free to share with your family and friends on social media.

I’ll see you all on the following recipe. Happy baking!

N x

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Bubbling Cauldron Cake

Bubbling Cauldron Cake

A cauldron shaped vanilla cake that is covered in buttercream and has real bubbling bubbles inside!

Serves 40

5 from 1 vote
Print Recipe Pin Recipe
Prep: 1 hour 30 minutes
Cook: 45 minutes
Total: 5 hours 30 minutes
Course: Dessert
Cuisine: American
Calories: 272kcal



  • 3 3/4 cups (645 g) all-purpose flour
  • 1 3/4 cups (400 g) caster sugar
  • 4 1/2 tsp baking powder
  • 3/4 tsp salt
  • 3/4 cup (190 g) unsalted butter
  • 3 large eggs
  • 2 1/4 cups (560 ml) milk
  • 3/4 cup (190 ml) vegetable oil
  • 3 tbsp greek yogurt
  • 1 1/2 tsp vanilla extract
  • 1 tsp lime flavoring
  • 5 drops each of teal and yellow food gel


Fondtant Decorations

  • 220 g (220 g) black fondant
  • 210 g (210 g) white fondant
  • 240 g (240 g) blue fondant
  • 300 g (300 g) purple fondant
  • 100 g (100 g) lime colored fondant
  • 100 g (100 g) yellow fondant

Learn How To Make it! [VIDEO]


Fondant Decorations (make in advance)

  • Cauldron Rim – 150g black fondant
    To make the cauldron rim, take 150g of the black fondant and roll out a 40cm log. That will go on top of the cake once it’s frosted and it’s best to roll it out fresh.
  • Cauldron handles – 50g black fondant
    Use 50g of the black fondant to roll out the fondant to a couple mm thin. Cut out two rectangles about 10cm in height and 6cm in width. Set aside. Roll out two logs with the remaining fondant measuring about15cm each. Place each end of the logs into the middle of each rectangle and press down into the rectangles. Fold the rectangle over the ends of the logs and press the rectangles together where they meet to seal it. Make these a day ahead to allow them to dry before adding to the cake.
  • Eyeballs – 110g white fondant, 20g blue fondant, 20g black fondant
    You’ll be making 4-5 eyeballs for the cake. Begin by rolling all but 10g of the white fondant into little eyeball sized balls using the palms of your hands.
  • Roll out the black, blue and remaining white fondant to a couple mm thin. Place a piece of plastic wrap over the top of each one and use the end of three different sized round piping tips.
  • Add a dab of water on top of the blue disc and add it to the white fondant ball. Use a food safe marker to draw lines on the blue fondant. Then place the black fondant on top before adding the tiny white disc on top of the black and blue fondant discs.
  • To finish draw some red lines on the white fondant ball using a food safe red marker. Make these a day ahead to allow them to dry before adding to the cake.

Fondant Tentacles (make in advance)

  • To make the tentacles use the purple fondant to rollout about 6 balls. Then roll out those balls to different lengths making sure one end is thinner and the other end thicker. Place each tentacle on to a baking tray lined with baking paper. You want to make them squiggly in shape.
  • Roll up about 20g of the blue fondant into about 50little balls in the palm of your hands. Then use the end of a ball shaped fondant tool to indent each ball. Add a little bit of water behind each one and stick it to the tentacles in a line from the base to the tip. Set aside to dry.Add a toothpick in the bottom of each tentacle and set aside to dry. Make the sea day ahead to allow them to dry before adding to the cake.

Lime Bubble Fondant Decorations (make in advance)

  • Roll the fondant into different shaped balls. Make these a day ahead to allow them to dry before adding to the cake.

Flames (make on the day you decorate)

  • Roll 100g each of the blue, yellow and white fondant into a log shape then twist them together a couple times before rolling out to a couple mm thin. Use different sized oval shape cookie cutters to cut out as many shapes as you can. Use smaller oval shaped cookie cutters to make curly and sharp shapes. It’s best to roll it out fresh.


  • Please note: to make the cake in this recipe, you’ll need to make 2 batches of vanilla cake. All other recipes and measurements are enough to put the cake together and decorate it.
    Preheat a fan-forced oven to 140C (280F) or 160C(320F) for a conventional oven. Spray two 8” cake tins and one 8” half sphere tin with oil spray and line the bottom with baking paper. You’ll need to place the half sphere cake tin on top of a circle cake tin so it stays put in the oven. Set aside.
  • Add the flour, sugar, baking powder and salt to a large mixing bowl and mix together using a hand mixer until well combined.
  • Next add the softened butter and mix on low speed until mixture reaches a crumbly sand like texture.
  • Add the eggs, milk, oil, lime flavouring, teal food gel, yellow food gel, Greek yogurt and vanilla extract. Mix on low speed until no dry ingredients are showing. Scrape down the bowl and mix for another 20 seconds.
  • Fill three cake tins with batter. You want to aim to fill them just above ¾ of the way.
  • Bake for 50-60 min or until a toothpick inserted comes out clean. If the pick comes out with wet batter, bake for a further 10 min at a time until fully baked. Allow the cakes to cool to room temperature inside the cake tins and then chill them in the fridge overnight. Chilling your cakes overnight makes them easier to trim and decorate. So I bake my cakes the day before I decorate them.
  • To trim your chilled cakes, use a cake leveller or large serrated knife to carefully trim the crust off the top of each 8” round cake and trim the very top of your sphere cake off so that it has a flat surface to sit on when it’s upside down. Then trim in half.
  • Let’s begin with the half sphere cake. Add a dab of frosting onto an 8” cake board or flat serving plate. Use a small offset spatula to spread the frosting around before adding smallest side of the half sphere cake. Gently press down the centre of the cake layer to make sure it’s stuck to the frosting underneath.
  • Add frosting to a piping bag and frost a ring around the top of the cake. Fill the centre with more frosting. Use your small offset spatula to smoothen out the frosting before you add Larger part of the half sphere cake on top.


  • Add black food gel to the chocolate buttercream frosting and mix until well combined. I’d recommend making the frosting in 3-4batches. Mix until well combined and evenly coloured. You’re going to use this frosting to fill, crumb coat and add a final coat to the cake.

Let's crumb coat!

  • To crumb coat the cake, add more frosting around theUse a small spatula to smoothen out the top and sides of the cake, taking care to fill in any gaps in between each layer of cake.
  • Place four bubble straws into the top of the cake, then carefully lift out a little to trim the excess off so they’re level with the top of the cake. Then press back into the cake. Place a 6” cake board on top of the cake and then add more frosting on top. Use a spatula to level off. Set aside in the fridge to chill for 4 hours.
  • To prepare the top half of the cake, use a large serrated knife to carve a curve into the top of the cake. Use a large round cookie cutter (about 5 inches) to cut out a circle in the centre top of the cake. Use a spoon to carve out a hold down to where the top of the bottom layer of cake starts. This is where you’ll place the cup that will be filled with dry ice and water to get that smoky effect.
  • Add more frosting around and top and sides of the cake including around the inside of the hole you carved. Use the small spatula to smoothen out the top and sides of the cake, taking care to fill in any gaps in between each layer of cake. Set aside in the fridge to chill for 4 hours.
  • To put the two halves together, pipe some black frosting on top of the half sphere cake. Carefully slip a spatula underneath the top half off the cake to remove the cake board.Place it on top of the half sphere cake. You already have a cake board on the half sphere cake so you won’t need another one.
  • Add some frosting around the side of the cake where there should be a gap between the top and bottom half of the cake. Use the spatula to smoothen out.

Let's decorate!

  • Add a final layer of frosting around the entire cake and use a spatula to smoothen it out.
  • Add the black fondant rim on top and use two toothpicks to secure the ends of the rim.
  • Add a small dab of black frosting on each end at about the half way mark of the cauldron. Stick the cauldron handles to it.
  • Carefully add the tentacles on top of the cake. Use more toothpicks to secure everything if you need to.
  • Add the bubbles and eyeballs in between the tentacles. Finish by adding the flames around the bottom of the cauldron.


This cake can be made up to three days in advance and can be stored in an airtight container.
Dry Ice
Add the shot glass in the cake before you add the tentacles.
Add the dry ice right before you’re ready to serve. To activate the ice add a couple pellets of dry ice into the shot glass and add about 15-20ml of water. The dry ice smoky effect only lasts about 10-20 seconds. To activate the dry ice again, simply add more water. You can do this about 2-3 times before you need to replace the dry ice.


Calories : 272kcal
Carbonhydrates: 31g
Protein: 2g
Fat: 13g
Saturated Fat: 7g
Polyunsaturated Fat: 3g
Monounsaturated Fat : 3g
Trans Fat : 1g
Cholesterol: 23mg
Sodium: 158mg
Potassium : 62mg
Fiber: 1g
Sugar : 20g
Vitamin A: 146IU
Calcium: 50mg
Iron: 1mg
Nutrition Disclosure
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