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Chromatica Cupcakes

These gorgeous rainbow jewel cupcakes are topped with a Japanese candy called Kohakutou. They’re agar agar jellies which when left to dry for 3 days, go frosty and crunchy on the outside, so yum and so easy to make!


  • Cupcakes
  • 430g (15 oz) plain (all-purpose) flour
  • 265g (91/2 oz) caster (superfine) sugar
  • 3 tsp baking powder
  • 1/2 tsp fine salt
  • 125g (41/2 oz/1/2 cup) unsalted butter, softened
  • 2 large eggs
  • 375 ml (121/2 fl oz/11/2 cups) full-cream (whole) milk
  • 125 ml (4 fl oz/1/2 cup) vegetable oil
  • 2 tbsp Greek yoghurt (or sour cream)
  • 1 tsp vanilla extract or vanilla bean paste
  • 1 tsp banana flavouring
  • 2 drops purple food gel
  • 2 drops green food gel
  • 2 drops pink food gel
  • 6 drops white food gel
  • Kohakutou
  • 15g Agar-agar
  • 400ml water
  • 680g sugar
  • 2 drops pink food gel
  • 2 drops green food gel
  • 2 drops orange food gel
  • 2 drops purple food gel
  • Frosting
  • 1 batch American buttercream frosting or Swiss meringue buttercream frosting
  • 1tsp banana flavouring
  • 4 drops purple food gel
  • 4 drops pink food gel
  • Decorations
  • 1 cup rainbow sprinkles


  1. Kohakutou
  2. Add the water and agar agar powder to a medium size saucepan and bring to a gentle boil while storing. Add the sugar and continue storing u til fully dissolved. Add the banana flavouring and mix until combined.
  3. Split the mixture in half. Split one half into 4 bowls. Colour each one using the food gel colours posted in the ingredients.
  4. Lightly spray and wipe down a rectangle container with oil spray. Pour the clear mixture into the container, the. Pour the coloured mixtures I’m and swirl around using a toothpick. Chill in the fridge for a hour before taking out. Slice into bra long ways and then use a sharp knife to cut into jewel shapes.
  5. Place on a baking tray lined with plastic wrap and allow to dry for 3 days. The jewels will go frosty and crunchy on the outside. You’ll want to have different sized jewels. Big ones and small ones.
  6. Cupcakes
  7. Preheat a fan-forced oven to 140°C (275°F) or a conventional oven to 160°C (320°F). Line two cupcake tins with the cupcake liners.
  8. Add the flour, sugar, baking powder and salt to a large mixing bowl and mix with a hand mixer until well combined.
  9. Next, add the softened butter and mix on low speed until the mixture reaches a crumbly, sand-like texture.
  10. Add the eggs, milk, oil, yoghurt and vanilla and banana flavouring and mix on low speed until all the dry ingredients are incorporated. Scrape down the side of the bowl and mix for a final 20 seconds. It’s at this point that you can add any flavourings or food-gel colourings to the batter.
  11. Add each coloured batter into a piping bag and pipe each colour into each cupcake liner, alternating between each one until you’ve filled them up just over ¾ of the way.
  12. Bake for 45 minutes. Once baked, allow to cool down completely.
  13. Frosting
  14. To prepare the frosting, add banana flavouring, pink and purple food gel and mix until well combined.
  15. Assembly
  16. Fit the end of a piping bag with a large round tip and pipe a bulb on top of each cupcake. Cover the frosting in sprinkles and then finish by sticking the jewels into the frosting.