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Chocolate Sponge Cake with Chocolate Buttercream

I cannot think of a situation or occasion when a light and fluffy chocolate sponge smothered in a smooth, creamy chocolate buttercream would not be appropriate!

Course afternoon tea, Dessert, Morning Coffee, Snack, treat
Cuisine British
Keyword buttercream, cake, Chocolate
Prep Time 20 minutes
Cook Time 22 minutes
Servings 10

Ingredients

For the cake:

  • 130g unsalted butter, at room temperature
  • 130g caster sugar
  • ¼ teaspoon fine salt
  • 2 large eggs
  • 1 tablespoon plus 1 teaspoon milk
  • 100g plain/all-purpose flour, sieved
  • 30g cocoa, sieved
  • 1¼ teaspoons baking powder
  • ½ teaspoon instant coffee

For the chocolate buttercream and topping:

  • 125g unsalted butter, at room temperature
  • ¼ teaspoon fine salt
  • 220g icing sugar, sieved
  • 30g cocoa, sieved
  • ½ teaspoon instant coffee mixed with 1 teaspoon hot water
  • ½ - 1 tablespoon milk

Topping:

  • 2 tablespoons chocolate shavings

Instructions

For the cake:

  1. Collect together your equipment (see Recipe Notes below) and ingredients.

  2. Preheat oven to Fan Oven 160°C/180°C/350°F/Gas 4

  3. Grease and line your cake tins or insert cake tin liners.

  4. Weigh the butter into a mixing bowl and ensure the butter is at room temperature and soft enough to beat. If not soften it slightly in the microwave. (Be very careful not to melt it though – just do 5 seconds at a time if you are unsure.)

  5. Add the salt, sugar, eggs and milk to the butter. Put the mixing bowl on the scales, balance the sieve on the bowl and zero the scales.

  6. Weigh the flour and cocoa directly onto the sieve and add the baking powder and coffee. Lift the sieve above the bowl and shake the sieve. You may need to use a spoon to press through any remaining lumps of cocoa.

  7. Whisk thoroughly with an electric whisk until just combined. This should take around 40 seconds - 1 minute and no more.

  8. Transfer to the prepared cake tins (see Recipe Notes) and cook in the centre of the oven for 18 - 22 minutes or until the sponge is cooked. It is cooked when:

    - the centre feels springy when lightly touched with your finger and no imprint remains

    - a toothpick inserted into the centre of the cake comes out clean

    - the cake is beginning to come away from the sides of the tin.

  9. Take out of the oven and leave for 5 minutes. Remove the cakes from the tins onto a cooling rack. Leave to cool.

For the chocolate buttercream and topping:

  1. Weigh the butter into a mixing bowl and ensure the butter is at room temperature and soft enough to beat. If not soften it slightly in the microwave. (Be very careful not to melt it though – just do 5 seconds at a time if you are unsure.)

  2. Whisk the butter and salt until light and fluffy. Put the mixing bowl on the scales, balance the sieve on the bowl and zero the scales. Weigh in half the icing sugar and sieve. Quickly fold in with a spoon (this is to stop the icing sugar clouding up and making a mess of your kitchen!) Whisk until light and fluffy.

  3. Repeat with the remaining icing sugar and beat well.

  4. Add the coffee and ½ tablespoon milk and put the mixing bowl on the scales, balance the sieve on the bowl and zero the scales. Weigh in the cocoa and sieve. You may need to use a spoon to press any remaining lumps of cocoa through.

  5. Quickly fold in with a spoon and then whisk thoroughly for a minute or two until light, smooth, creamy and fluffy. If necessary, add some extra milk.

Assemble the cake:

  1. Put some strips of foil or baking parchment on a plate. Turn one of the cakes up side down and place in the centre of a serving plate so the flat side faces up. Ensure there are strips of foil or parchemnt under the edges of the cake. You will remove these, they just help to keep the plate clean.

  2. Spread roughly ⅓ of the buttercream over the cake ensuring you spread it to the edges.

  3. Place the second cake on top, flat side down.

  4. Use the remaining buttercream to spread over the top and sides of the cake. Use your knife to make a decorative swirling pattern

  5. Scatter over chocolate shavings. (I make these by using a potato peeler to shave chocolate off the side of a block of chocolate.)

Recipe Notes

Equipment

  • 2 x 7inch round cake tins, greased and lined with baking parchment or a cake tin liner
  • kitchen scales and measuring spoons
  • mixing bowl
  • electric whisk
  • baking dish/cake tins
  • sieve
  • cooling rack

Balancing the cake tins:

  • It is important that both tins have as equal amount of batter as possible. You can do it by eye but this is a really simple way to be accurate. To do this, I:
  • put a cake tin on the scales and zero the scales
  • add half the batter - it should weight between 255g - 260g. Take off the scales
  • place the second empty tin on the scales and check it has gone back to zero
  • add the remaining batter and check it is the same weight. If not adjust. 

For a larger cake, use 3 eggs and 2 x 8 inch cake tins:

  • 195g unsalted butter
  • 195g caster sugar
  • 3 large eggs
  • 150g plain/all-purpose flour
  • 45g cocoa
  •  1¾  plus ⅛ teaspoon baking powder
  • ¾ teaspoon instant coffee
  • ¼ plus ⅛ teaspoon fine salt
  • 1½ tablespoons milk