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Rainbow Cake with Lego


For 6 cake layers

  • (halve the mixture and make 3 layers at a time. It is a lot easier to manage)
  • 4 1/2 cups self-raising flour
  • 2 1/2 cups caster sugar
  • 500 g butter , melted
  • 2 cups milk
  • 8 eggs
  • 2 teaspoons vanilla extract
  • food colouring in red , yellow and blue (see notes)

For the vanilla icing

  • 500 g butter , softened (not melted)
  • 4 cups (640g) icing sugar
  • 2 teaspoons vanilla extract

For the fondant lego

  • fondant in RED , YELLOW, GREEN and BLUE


For the cake

  • Preheat oven to 180 degrees C (350 degrees F). If making 3 layers at a time, grease 3 cake tins; set aside. Place flour and sugar in a bowl and beat until fluffy. Add vanilla and eggs one at a time. Alternate adding the flour and milk and while beating ending in the flour.
  • Using scales, divide the mixture into 3 bowls. If you don't have scales use a cup to scoop out the mixture, cup at a time into the 3 bowl until it is divided evenly. Add the food colouring for the suitable layer and pour into the greased cake tins. Bake for approximately 30- 40 minutes or until cooked through. Test with a skewer or sharp knife. Cool slightly in the tin and turn out onto a wire rack to cool completely. Repeat steps to make the other 3 layers if necessary.

For the icing

  • Place softened butter in a bowl and using an electric mixer, beat for approximately 5 minutes or until creamy. Add icing sugar and vanilla and beat for a further 10 minutes until light and fluffy

To assemble the cake

  • Cut the tops of all the cakes. Place your purple layer on the plate you will serve it on and spread a good layer of the icing over the layer. (you can see from my pictures I didn't use a huge amount of icing in-between each layer) Repeat with all the layers. Then spread a VERY thin layer over the entire cake (called the crumb layer). Fridge the cake now to set all the crumbs in this layer. Once cold the icing will set hard. This makes it a lot easier to ice and prevents you getting crumbs in your icing. Remove from the fridge and add the remaining icing and smooth using a large knife.

For the fondant Lego

  • Roll out the fondant to a thickness of about 12mm (half and inch). Then using a sharp knife cut it into rectangles about 30mm x 15mm (1 1/4 inch by just over 1/2 inch). With the off cuts roll it out so it is a couple of millimetres thick and using a round 7mm plunger cutter (available from baking shops) cut the 6 circle and place on top of the rectangles as you go. Use a little water to moisten the top if they aren't sticking. The lego will stick to the cake icing no problems.
  • If making the cake a day or two ahead of time, keep in the refrigerator unit the day. Bring to room temperature before serving.


Please note an Australian cup is based on a 250ml cup.
Food colouring for the cake layers: AmeriColor works really well to get the intense colours. I used colours: 106 Electric Blue, 107 Lemon Yellow, 119 Red Red. If buying small bottles I would recommend buying a larger bottle of the red as you will use the most of this colour.
Cake colour mixes: Red layer: just pure red. Orange layer: Yellow and Red. Yellow layer: pure yellow. Green layer: Yellow and Blue. Blue layer: Pure blue. Purple layer: Red and Blue - I used to much of both colours and it was too dark.