LOUISE CAKE BASE

1. Preheat the oven to 350°f/180°c. Grease and line an 9" (23cm) pan with parchment paper that extends over both sides to form a 'sling'. Secure with metal binder clips if desired. 
2. In a medium bowl, cream together the butter and sugar with an electric hand mixer on medium-high speed until light and fluffy. Add the egg yolks and vanilla and mix to combine. Add the salt, baking powder, and flour, and mix on low speed until just combined, then finish by hand to ensure the mixture is not over mixed. Alternatively you can use the stand mixer with the paddle attachment to make the base mixture.
3. Transfer the base mixture into the prepared tin. To do this I find it easiest to crumble the base mixture evenly in the pan, then pat down with my hands or the bottom of a flat measuring cup or drinking glass to ensure it is as flat and even as possible. 
4. Once the base mixture is smooth, top with the raspberry jam and spread to create an even layer. Leave to sit while you prepare the Swiss meringue topping. 

COCONUT SWISS MERINGUE TOPPING

1. Measure the egg whites and sugar into the bowl of a stand mixer or other heatproof bowl. Place over a pot of simmering water, ensuring that the water does not touch the bottom of the bowl. Heat the mixture, whisking often and watching the edges carefully, until it no longer feels gritty when rubbed between your fingers, and it registers at least 160°f / 70°c on a thermometer.
2. Remove the bowl carefully from the double boiler, and whip with either an electric hand mixer or a stand mixer fitted with the whisk attachment, until the mixture is thick, glossy and white, and is just starting to form stiff peaks, 3-5 minutes depending on what equipment you are using (it took me 5 minutes with a handheld electric mixer). Add the vanilla and mix to combine. 
3. Add the coconut to the Swiss meringue and fold to incorporate. 
4. Spread the coconut meringue over the base of the Louise cake and spread evenly. Try not to have any little peaks of meringue poking up as these will bake unevenly in the oven. 
5. Bake the Louise cake for 30 to 35 minutes, until the meringue is golden brown. The meringue will puff up, then sink down once removed from the oven. Place on a wire rack to cool.
6. Allow to cool completely before using the parchment paper to remove from the pan and slicing into squares or rectangles using a sharp knife which has been run under hot water then wiped dry. Wipe the knife blade between cuts.
7. Store leftovers at room temperature in an airtight container for up to three days.