1⁄2 cup buttermilk
1⁄2 cup sour cream
2 tbsp lemon juice
250g butter, softened
1 1⁄2 cups caster sugar
1 tsp vanilla bean paste
2 tbsp lemon zest
2 cups self-raising flour
600ml thickened cream
2 tbsp icing sugar
A selection of citrus fruits – for example, oranges, blood oranges, limes, lemon, mandarins, grapefruit – cut into slices
Citrus Curd (makes approx 1 1⁄4 cups)
2 egg yolks
1 cup caster sugar
1 tbsp lemon zest
1⁄2 cup citrus juice (try a blend of different citrus fruits)
125g butter, chopped
Preheat oven to 180°C. Grease and line 2 lamington slice tins, measuring 20cm x 30cm and 2.5cm deep. Extend the paper over the long ends of the pan by 5cm, this will help you to remove the cake later.
In a large bowl, whisk together buttermilk, sour cream and lemon juice, set aside.
In a large bowl of a stand mixer, place butter, sugar, vanilla and lemon zest. Using a paddle attachment, beat on a medium speed for 2-3 minutes or until light and creamy. Add eggs, one at a time, beating well after each addition. Gently fold in half the flour, then half of the buttermilk mixture. Repeat until remainder is used.
Divide mixture evenly into the prepared pans. Spread with an offset spatula to level the batter. Bake for 25 minutes or until cake is cooked, swapping trays around after 15 minutes so cakes cook evenly.
To test, insert a wooden skewer into the centre, if it comes out clean it is cooked. Allow cakes to sit in the tin for 10 minutes, then remove and allow to cool completely on cooling racks.
Meanwhile, prepare the citrus curd. Place eggs, egg yolks, sugar, lemon zest and juice into a medium bowl. Whisk to combine. Pour into a medium saucepan and stir mixture over a low-medium heat for 2 minutes to dissolve the sugar.
Reduce heat to low, then gradually add the butter a few cubes at a time, stirring constantly to melt. Continue stirring over heat for 5-6 minutes or until mixture has thickened enough to coat the back of a spoon. Strain into a heatproof bowl, cover with plastic wrap and chill until cold.
To decorate, trim the edges of the cake with a sharp knife. Using the stand mixer, with a whipping attachment, whip cream and icing sugar for about 2-3 minutes or until thickened. Place one cake onto a serving platter, spread with 2⁄3 of the lemon curd, and half the cream. Top with the other cake. Spread with remaining cream and drizzle with citrus curd.
Decorate with citrus slices. Slice cake to serve.
The citrus curd can be made in advance. Store in an air-tight container and chill in the fridge for up to one week. Or, if preferred, buy a good quality ready- made lemon curd.