- 650g all-purpose flour
- 400g caster (superfine) sugar
- 4.5 tsp baking powder
- 3/4 tsp salt
- 185g unsalted butter, softened
- 650ml of milk
- 185ml vegetable oil
- 3 large eggs
- 2 tsp bubblegum essence
- black: 3 tbsp cocoa powder + 4 drops black food gel
- purple: 3 drops purple food gel + 2 drops pink food gel
- green: 4 drops teal food gel + 4 blue teal food gel
- 2 batches Swiss meringue buttercream frosting (recipe: thescranline.com)
- 2 tsp bubblegum essence
- light blue: 10 drops blue food gel
- medium blue: 5 drops blue food gel + 5 drops teal food gel
- dark blue: 5 drops purple food gel
- midnight: 5 drops black food gel
- Preheat a fan-forced oven to 160C (320F) or 180C (356F) for a conventional oven.
- Spray two 7” cake tins with oil spray and line the bottom with baking paper.
- In the bowl of a stand mixer fitted with the paddle attachment, add the flour, baking powder, caster sugar and salt. Turn mixer on low speed and allow it to mix for a couple minutes to help everything combine well (alternatively you may do this by sifting the ingredients together). Add the softened butter and mix until it resembles a fine sand like texture.
- Add the milk, oil, bubblegum essence and eggs into the bowl with the dry ingredients and mix on medium speed until no dry ingredients are visible. Scrape down the bowl and mix for another 20 seconds.
- To colour the frosting use the colour formulas in the ingredients list to colour black, green and purple into three bowls.
- Fill three 7” cake tins with batter by randomly spooning each colour into the cake tins with a tablespoon. Gently tap the cake ton to settle the batter and flatten it.
- Bake for 45 min or until a toothpick inserted comes out clean.
- Allow the tins to cool for 2 min and then carefully flip the cake tins over on to a cooling wrack to cool completely before using.
- Chill for 4 hours or overnight before using.
- Using a large serrated knife, carefully trim the top off each layer of cake to make even and flat layers. Try to aim to get them all the same height. An easy way to do this is to find the lowest height of the cake, place a skewer or toothpick next to that point and mark it. As you go around each side of the cake cutting it, use the marked skewer to make sure each cut is at the same height. You’ll end up with two layers from each cake tin. So 4 layers of cake in total.
- To prepare crumb coat, add a dab of frosting onto an 8” cake board or serving plate. Add first cake layer. Use a small offset to add a layer of frosting and smoothen out and layer the frosting on each layer before adding the next layer of cake. Add more frosting around the outside to fill the grooves between each layer. This should just be a neat thin layer of frosting which is aimed at trapping any cake crumbs so that random bits of cake crumbs don’t show up on the outside of the cake.
- Chill for 2 hours or overnight
- Set 2 tbsp of frosting aside in a small bowl.
- So the way we’re going to colour the frosting is by starting with the lightest shade, take some of that out then add more colour to darken the frosting. So begin by adding the blue food gel and bubblegum essence to the remaining buttercream, mix using a hand mixer or in a stand mixer (a hand whisk will not work, you need high speed whisking to get the colour to mix in properly)
- Set ¼ of the frosting aside before you add the next lot of colour for the medium shade of blue, followed by the dark shade and midnight blue. So you’ll end up with 4 bowls of frosting each with a different shade.
- Add each shade to a piping bag and snip off the end.
- Begin by frosting the lightest shade of blue frosting around the bottom of the. Then use the next shade, followed by the dark blue and finish with the midnight blue.
- Use a small offset spatula to evenly spread the frosting around the top. Then use a bench scraper to go around the cake to smoothen out the sides. You may need to go around the cake a couple times so make sure you scrape off the excess frosting each time avoid mucking up the blue ombre.
- To finish add some of the white frosting to set aside in the beginning into a piping bag fitted with a small round tip. Pipe some random dots of frosting toward the top of the cake and then pipe random lines connecting some of the dots. Finish off by piping some star dots on the top of the cake.