Mars bar celebration cake

Following the success of my Mars bar frosting, I decided to make a Mars bar cake with an Italian buttercream filling to represent the nougat part of Mars bars. It helps to melt the chocolate and mars bars for the Mars bar frosting first and set aside while you make the Italian buttercream filling as you need to add 2 tablespoons of the chocolate for this filling.

The cake will keep for three days at room temperature in a sealed container. Do not store in the fridge.

Makes 1 large layer cake |Baking time 25-30 minutes| Requires a sugar thermometer

Moist chocolate sponge

1/2 cup (50 grams) cocoa
1 cup (250 mls) boiling water
4 large eggs separated
1 cup (220 grams) white granulated sugar
1/3 cup (67 grams) soft light brown sugar
1/2 cup (125 mls) sunflower oil
1 teaspoon vanilla extract
1 3/4 cups (260 grams) flour
1 tablespoon baking powder

  1. Preheat oven to 180 degrees Celsius
  2. Grease two 22-23 cm round cake tins
  3. Mix cocoa and boiling water together and stir until smooth – set aside
  4. Beat egg whites with an electric whisk until stiff – set aside
  5. Beat egg yolks and sugar together until thick and fluffy (about 2 minutes)
  6. Add oil and vanilla to cocoa mixture
  7. Add cocoa mixture to egg yolk mixture and mix until combined
  8. Sift flour and baking powder together and fold into egg yolk mixture
  9. Finally fold in egg whites with a metal spoon by first mixing in a large spoon of egg whites and then folding in the remaining egg whites
  10. Bake for 25-30 minutes or until a cake tester comes out clean
  11. Cool for 5 minutes in the tin before turning out to cool completely

Mars bar frosting

240 grams mars bars (about 4 or 5 mars depending on sizing – keep extra for decoration)
75 grams dark chocolate
1/2 cup (125 mls) cream
125 grams unsalted butter – softened

  • Add cream and chocolate broken up into pieces to a double boiler/pot over boiling water and melt chocolate over boiling water. Stir until melted and smooth (its fine to have a few nougat bits in it but if you continue to stir it should all dissolve and become silky smooth)
  • Remove from heat and leave to cool, stirring occasionally – reserve 2 tablespoons for the filling and start making the filling now
  • Once cool, using an electric whisk beat in softened butter until fluffy (no need to wash the bowl and beaters after making the filling for this part)
  • Refrigerate for 1 hour before frosting the cake (if the frosting is too hard to work with, dip a palette knife/icing knife into boiling water and then frost the cake)

Italian buttercream filling

120 grams castor sugar (a little under 1/2 cup)
1 tsp golden syrup
2 tablespoons water
2 large egg whites
200 grams unsalted butter softened
2 tablespoons reserved mars choc ganache (without the butter)

  • Add sugar, syrup and water to a large saucepan and mix, use a brush to remove sugar from sides of saucepan. Set over high heat and bring to a boil
  • Remove from heat once it reaches 120C on a sugar thermometer
  • While you are cooking the sugar, whisk the egg whites until soft peaks form then slowly pour in the sugar mixture while whisking. Continue to beat until the mixture cools slightly (note make sure you have a clean and dry bowl for beating the egg whites)
  • Add a third of the butter at a time and whip until fully incorporated
  • Add the reserved mars bar chocolate and whip

To assemble the cake

  • Divide each sponge in half horizontally so you will have a four layer cake
  • Spread each layer with a third of Italian buttercream
  • Top with mars bar frosting and spread around the sides of the cake, if the frosting is too hard to work with, dip a palette knife/icing knife into boiling water and then frost the cake
  • Decorate with thinly sliced mars bars sprinkled on top of the cake if desired

If you like this recipe, you might like:

Salted caramel brownies

Salted caramel brownies

Snicker bar cupcakes