Don’t over-beat the filling or it will split, making it look curdled. Filled lamingtons can be made up to four days ahead. Keep in an airtight container in the fridge.
6 eggs, at room temperature
1 cup brown sugar, firmly packed
1 cup self-raising flour
1⁄2 cup plain flour
2 tblsps boiling water
2 1⁄2 cups shredded coconut
1 1⁄2 cups desiccated coconut
1 1⁄4 cups thickened cream
225g packet Jersey caramels, chopped
4 cups icing sugar mixture (580g)
1⁄2 cup cocoa powder
50g unsalted butter, chopped
3⁄4 cup milk
Grease a 19cm x 30cm lamington pan. Line base and sides with baking paper, extending paper 3cm above pan edges.
2 To make filling, combine cream and caramels in a medium saucepan over a low heat. Stir until caramels are melted and mixture is smooth. Don’t boil. Transfer to a large heatproof bowl. Cover surface with plastic wrap. Refrigerate until cold.
3 Beat eggs in a large bowl of an electric mixer on high speed for about 7 minutes, or until thick and creamy. With motor operating, gradually add sugar, 1 tblsp at a time, beating until dissolved.
4 Sift flours twice onto a sheet of baking paper. Sift again over egg mixture. Add water. Using a whisk, gently fold until just combined. Pour into pan. Spread to corners.
5 Cook in a moderate oven (180C) for about 25 minutes, or until golden brown and sponge springs back when lightly touched. Invert onto a wire rack lined with baking paper. Cool completely.
6 To make icing, sift sugar and cocoa into a large, heatproof bowl. Add butter and milk. Sit bowl over a pan of simmering water. Whisk until smooth. Remove. Cool slightly.
7 Cut sponge into 15 equal squares. One at a time, dip in icing, allowing excess to drain off. Roll in combined coconuts. Place on a wire rack to set.
8 Beat filling with an electric mixer for about 1 to 2 minutes, or until light and fluffy.
9 Cut lamingtons in half. Sandwich together with filling.