Method

• 1.
  Preheat oven to 160°C/140°C fan-forced. Grease 2 x 18cm round cake pans and line base and side with baking paper
• 2.
  In a stand mixer fitted with the whisk attachment, whisk egg yolks and 1/2 cup (110g) sugar until thick and pale, then whisk in yoghurt and butter. Transfer to a large bowl and set aside.

• 3.
  Add egg whites to cleaned mixer bowl and whisk on medium-low speed until soft peaks, but not stiff. Add remaining 3/4 cup (165g) sugar, 1 tbs at a time, until mixture is thick and glossy, but not stiff. Add 3 tsp zest to yolk mixture, then add flour, juice and cardamom and stir to combine. In 3 batches, fold egg whites into yolk mixture until combined. Divide mixture between pans. Tap on the bench to release any big air pockets. Bake for 45 minutes, or until golden. Cool in pan for 20 minutes, then invert onto a wire rack and cool completely.
• 4.
  For the icing, place egg whites and sugar in a heatproof stand mixer bowl set over a saucepan of gently simmering water (don’t let base of bowl touch the water). Stir with a whisk until sugar has dissolved and mixture is hot, then transfer to stand mixer fitted with the whisk attachment and whisk on high speed for 6-8 minutes, until completely cooled and mixture is thick and glossy. Stir in food colouring to desired shade of pink.
• 5.
  Arrange one cake on a serving platter. Spread 1/2 cup icing over the cake and top with second cake. Spread icing over top and side with an offset spatula, leaving some gaps around the base. Serve immediately.