This gorgeous banana, vanilla and choc chip wallpaper sheet cake is inspired by a wallpaper pattern I saw on Pinterest the other day. It was so gorgeous I decided to make it into a cake!

Serves 20





  • 630g (3 ¼ cups) plain (all-purpose) flour

  • 390g (1 ¾ cups) granulated sugar

  • 4.5 tsp baking powder

  • 1/2 tsp fine salt

  • 190g (¾ cups) unsalted butter, softened

  • 3 large eggs

  • 562ml (2 ¼ cups) full-cream (whole) milk

  • 190ml (¾ cup) vegetable oil

  • 3 tbsp Greek yoghurt (or sour cream)

  • 1 ½ tsp vanilla extract or vanilla bean paste

  • 2 ripe bananas, mashed

  • 1 cup mini semi-sweet choc chips

  • 1 tsp cinnamon


Simple Syrup

  • ¼ cup sugar

  • ¼ cup water

  • 1 tsp vanilla extract



  • 2 batches Vanilla flavoured American buttercream frosting

  • 2 tsp banana flavouring

  • Black frosting: 1 tbsp cocoa powder + 5 drops black food gel

  • Pink frosting: 5 drops red food gel + 5 drops pink frosting

  • Light yellow frosting: 2 drops yellow food gel

  • Yellow Frosting: 6 drops yellow food gel

  • Dark Yellow Frosting: 6 drops yellow food gel + 3 drops orange food gel



Prepare the frosting by adding the banana flavouring. Mix until well combined.


Split the frosting into three. Make the pink frosting by adding the food gels listed in the ingredients list. Mix with a spatula or hand mixer until well combined.


Colour another portion light yellow using the colour combination in the ingredients list.


Split the remaining frosting into 4 bowls. You’re going to leave one portion white. Colour the remaining portions yellow, dark yellow and black.



Preheat a fan-forced oven to 140C (280F) or 160C (320F) for a conventional oven. Spray a 30.5 x 20.5 x 2.8 cm cake tin 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, mashed banana, cinnamon, 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. Add the choc chips and fold in using a spatula.


Pour the batter into the cake tin. 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 cake to cool to room temperature inside the cake tins and then chill it in the fridge overnight. Chilling your cake overnight makes it easier to trim and decorate. So I bake my cake the day before I decorate it.


To trim your chilled cake, use a cake leveller or large serrated knife to carefully trim the crust off the top.


To crumb coat your cake, add a dab of frosting onto an 45cm x 30cm rectangle cake board. Use a small offset spatula to spread the frosting around before adding the trimmed cake layer. Gently press down the centre of the cake layer to make sure it’s stuck to the frosting underneath.


Add light yellow frosting to a piping bag and frost around the sides and the top of the cake. Fill the centre with more frosting. Use your small offset spatula to smoothen out the frosting before you add the next layer of cake. Repeat with the remaining layers.


Add more frosting around the top and sides of the cake. 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.


Use a cake scraper (otherwise known as a bench scraper) to smoothen out the frosting on the sides and top. Get it as neat as you can. 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 final layer of frosting. Chill for 2 hours or overnight.


Add the pink frosting on the top and sides of the cake and smoothen out using the bench scraper. Chill for 2 hours.


Fit the end of 5 small piping bags with a Wilton #3 piping tip ad fill with white, black, yellow, light yellow and dark yellow frosting.


Use a toothpick to indent the top of your chilled cake with banana patterns as shown in the video. Then slowly fill in the bananas with coloured yellow frostings and the white for the open part of the open bananas. Then finish by outlining the bananas with the black frosting.





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Hey there! My name is Nick Makrides! I'm guessing you love baking as much as I do which is how you stumbled upon my website!


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