Step 5: Divide the whisked egg mixture into three bowls. Working with one bowl of egg mixture, flour and butter at a time, sift the flour over the egg mixture and gently fold in. Add the butter and fold – work quickly to prevent it collapsing.

Step 6: Repeat Step 5 with the remaining bowls of egg mixture, flour and butter to give three mixtures – vanilla, raspberry and lemon. Pour each into a section of the cake tin and bake for 12-15 minutes, until the tops spring back when pressed. Cool a little in the tin, then transfer to a wire rack to cool completely.

Step 7: For the Italian meringue buttercream, melt the sugar in 3 tablespoons of water very gently in a pan over a low heat. Meanwhile, whisk the egg white in the clean bowl of a stand mixer fitted with a whisk, to soft peaks. Once the sugar has completely dissolved, increase the heat to a rapid boil until the syrup reaches 121°C on a sugar thermometer.

Step 8: Remove the pan from the heat. With the whisk at full speed, slowly pour the hot syrup on to the egg whites in a thin stream. Continue whisking until the meringue is very thick and glossy and has cooled to room temperature.

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