Created by ImPat on December 3, 2020
Step 1: Preheat oven to 180°C/160°C fan forced.
Step 2: Grease a 16 x 25cm slice pan and line base and sides with baking paper.
Step 3: Sift self-raising and plain flours and custard powder into a bowl.
Step 4: Beat sugar and butter in a large bowl for 2 minutes or until pale and creamy and then add oil and vanilla and beat until combined and now add eggs, 1 at a time, beating well after each addition and then add sour cream and flour mixture and beat, scraping down side of the bowl, until just smooth.
Step 5: Pour into prepared pan and bake for 25 minutes, until golden and cake springs back when lightly touched and set aside for 10 minutes to cool slightly and then turn onto a wire rack to cool completely.
Step 6: To make buttercream, whisk egg whites and sugar in a heatproof bowl until combined and place bowl over a saucepan of simmering water (make sure bowl doesn’t touch water) and cook, stirring occasionally, for 3-5 minutes or until hot to touch.
Step 7: Use a stand mixer with whisk attachment to beat on high for 10 minutes or until almost at room temperature and then swap to paddle attachment and beat in one-third of butter and repeat with remaining butter in 2 more batches before beating in brandy.
Step 8: Transfer the buttercream to a piping bag fitted with a plain nozzle. Pipe over the cake then sprinkle with nutmeg to serve.