Lovely lemon sponge slice

Lemon Sponge Slice

This is a light lemon sponge topped with a lemon curd buttercream. I used the French method for the buttercream but you could just whip cream and fold in lemon curd for the frosting. I served as individual squares but the cake recipe can easily be made into a layer cake.

Makes 32 cake squares|Baking time 20-25 minutes|Suitable for freezing

Lemon sponge

4 large eggs separated
1 cup (220 grams) granulated white sugar
1/4 cup (62mls) sunflower oil
1 tablespoon lemon zest
1 tablespoon freshly squeezed lemon juice
1 1/4 cups (190 grams) flour
2 teaspoons baking powder
pinch salt
1/2 cup (125mls) boiling water


  1. Preheat oven to 180 degrees C (375 degrees F). Grease the base and sides as well as line the base of two 20cm square cake tins.
  2. Sift flour, salt and baking powder together and set aside
  3. Beat eggs white until stiff and set aside
  4. Beat egg yolks and sugar on high speed until fluffy, then add oil, lemon rind and juice and beat on medium speed until combined
  5. Add flour to oil mixture and mix with a spoon until just combined
  6. Add boiling water and mix lightly until combined
  7. Fold in half of the egg whites and then fold in the remaining half with a metal spoon
  8. Divide the mixture between the tins and bake for 20-25 minutes or until a cake tester comes out clean
  9. Cool for 5 minutes in the tins before turning out onto a wire rack to cool completely

Lemon curd buttercream

5 -6  tablespoons of  home-made lemon curd or bought lemon curd plus extra for decorating
2 egg yolks
1/3 cup (70 grams) granulate white sugar
50 mls water
125 grams unsalted butter softened
1 tablespoon lemon zest


  1. Beat egg yolks until fluffy
  2. Heat sugar and water until dissolved and bring then bring to soft boil stage (115 degrees C)
  3. Gradually pour over the hot syrup on to the egg yolks while constantly beating and beat until thick. Leave to cool completely
  4. Once completely cool, beat butter and lemon zest and then gradually add the egg yolk mixture and beat until smooth and fluffy
  5. Beat in 5-6 tablespoons of lemon curd depending on desired taste
  6. Spoon over cooled cake and smooth with a palette knife
  7. If desired, cut each cake into 16 squares and top each square with a teaspoon of lemon curd
  8. Alternatively serve as one layer cake topped with a thin layer of lemon curd on top of the butter-cream or in the middle of the cake