Ingredients
Cake
- 430 g 15 oz plain (all-purpose) flour
- 265 g (91/2 oz) caster (superfine) sugar
- 3 teaspoons baking powder
- 1/2 teaspoon fine salt
- 125 g (41/2 oz/1/2 cup) unsalted butter, softened
- 2 large eggs
- 375 ml (12½ fl oz/11/2 cups) full-cream (whole) milk
- 125 ml (4 fl oz/1/2 cup) vegetable oil
- 2 tablespoons Greek yoghurt (or sour cream)
- 1 teaspoon vanilla extract or vanilla bean paste
- 2 cups confetti rainbow sprinkles
Rainbow marshmallows
- 3 cups granulated sugar
- 6 tbsp gelatin powder + 1 1/3 cup cold water
- 1 1/3 cup hot water
- 2 tsp vanilla extract
- 3 drops yellow food gel
- 3 drops green food gel
- 3 drops blue food gel
- 3 drops purple food gel
- 3 drops pink food gel
- 3 drops orange food gel
Frosting
- 1 batch swiss meringue buttercream frosting
- 3 drops yellow food gel
- 3 drops green food gel
- 3 drops blue food gel
- 3 drops purple food gel
- 3 drops pink food gel
- 3 drops orange food gel
Decorations
- 1 cup large rainbow confetti sprinkles
- ½ cup large rainbow confetti sprinkles
- ½ cup large rainbow confetti sprinkles
- Steps
Cake
- To make the 6 layered 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 three 8” cake tins with oil spray and line the bottom with baking paper. 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, 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 8” cake tins with batter. I find using an ice cream scoop to help me do this makes it easy to distribute the batter evenly so that everything bakes at the same time. Pour 1/3 of the sprinkles into each cake tin and mix into the batter.
- 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.
- Allow the cakes to cool to room temperature in the tins, then chill them in the fridge overnight. Chilling your cakes overnight makes them easier to trim and decorate, so I always bake my cakes the day before I decorate them.
- To trim your chilled cakes, use a cake leveler or large serrated knife to carefully trim the crust off the top of each cake before you trim each cake in half. You’ll end up with 6 layers of cake.
- This cake is a lot easier to make than most other cakes, because you don’t need to crumb coat, chill, then add a final layer. Instead we’re going to fill the cake inside a tube that you’ll create using acetate. Acetate is a plastic sheet. You’ll need a piece measuring about 29cm in height and 70cm in length.
- Place the plastic sheet inside an 8” cake tin. Use sticky tape to stick it to the cake tin. Also, take care to stick the two ends together so that it all stay together as you’re filling it. Do your best to make sure the plastic sheet stands straight and isn’t slanted. If it’s a little slanted, don’t worry, it will straighten out when you start filling it.
- Place the first layer of cake in the plastic tube. Then pipe a layer of purple frosting. Gently tap the cake tin against your workbench and repeat with each colored frosting in the order of the rainbow until you get to the final layer. Finish with the final layer of cake and the pink frosting on top. Chill the cake in the fridge for 5 hours. Overnight is best.
- Take the cake out of the cake tin and cut the tape away from the cake to unwrap it from the acetate plastic.
- Add large sprinkles down he bottom of the cake. If you find that the sprinkles won’t stick to the cake add a little bit of frosting behind the sprinkles to help them stick to the cake. Add medium from the bottom of the cake to about half way and then add the smaller sprinkles from the bottom of the cake to the top. This will help you get an Ombre of sprinkles effect.
- Finish by adding the marshmallow squares on top.
Rainbow marshmallows
- Grease a 4cm deep, 20cm x 20cm baking tin slab pan. Line the base and sides with baking paper, allowing a 3cm overhang at both long ends.
- Combine sugar and hot water in a saucepan over medium heat. Cook, stirring for 3 minutes or until sugar dissolves and syrup is clear.
- Using a whisk or fork, combine gelatin and cold water in a jug. Pour this mixture into the hot syrup. Cook, stirring, for 2 to 3 minutes or until gelatin has dissolved and mixture is clear. Pour into bowl and set aside to cool to room temperature (about 30 minutes). If the gelatin sets, pop it in the microwave for 15 seconds to liquify again and allow to cool for 5 minutes.
- Using a stand mixer, beat sugar and gelatin mixture on high for 6 to 10 minutes or until very thick. Add vanilla and food coloring to reach desired color and beat for 1 minute.
- For this next bit, you’ll need to work quickly, because the gelatin can set quickly.
- Split the mixture into 6 different bowls. Add each food gel into each one and use an electric mixer to mix the color in. If you find your marshmallow mixture is setting, microwave it for 10 seconds to help soften it.
- As you pour each layer into the prepared pan, make sure it’s not set. It needs to be about the same consistency as cake batter. That’s why microwaving it might be a good idea to be able to reach that consistency. Begin by adding the purple, followed by the blue, green, yellow, orange and finish with the pink. Add some sprinkles on top before you add it to the fridge to set for 4 hours.
- Once it’s set, lift it out of the cake tin and use a large knife to cut into squares. Please note: the marshmallows need to be put on the cake no longer than a couple hours before serving otherwise they will begin to dry out.
Frosting
- To prepare the frosting, split into 6 large mixing bowls.
- Add each separate food gel color and mix using a hand mixer until well combined.
- Add each one into a piping bag and set aside.