150g unsalted butter, at room temperature
2/3 cup caster sugar
3 free-range eggs
2 free-range egg yolks
1/4 cup lemon juice
2 tsp vanilla paste
1 cup plain flour
1/4 cup self-raising flour
1/2 tsp baking powder
Yellow and green gel food colourings
1/4 cup apricot jam
1/2 cup milk
2 Tbsp pure icing sugar, sifted
Golden syrup and crumbled chocolate biscuits, to serve
Preheat oven to 160°C fan-forced (180°C conventional). Line two 17 x 27cm slice pans with baking paper. Combine butter and caster sugar in bowl of an electric mixer and beat with paddle attachment on medium speed for 5 minutes, until light.
Whisk eggs, yolks, lemon juice and half of the vanilla in a bowl, and add to butter mixture with mixer running. Sift flours and baking powder together, then fold in gently.
Put two-thirds batter in one bowl and tint yellow. Put remainder in another bowl and tint green. Spread each batter in a prepared tray. Place in oven together and bake green cake for 12 minutes, and yellow cake for 17. Cool yellow cake upside down and green right side up on wire racks.
Boil jam and spread over yellow cake. Put green cake on top. Trim edges of cake and cut into 6 bars.
Warm milk with icing sugar and remaining vanilla. Foam with a frother. Top cakes with milk froth (soap suds), golden syrup (detergent) and crumbled biscuits (washing-up mess), to serve.