For the macaron shells mix in a large bowl the icing sugar and almond meal. Sift the almond meal and icing sugar mixture ensuring that there are no lumps of icing sugar and no large peaces of almond meal, the rule is if it doesn’t fit through the sieve don’t use it. Set the sifted dry mixture aside and beat egg whites on medium speed until soft peaks form. Once soft peaks form slowly add the caster sugar slowly to the egg whites wile it is still beating. To ensure that all the caster sugar has dissolved in the egg whites allow it to beat for a further minute after the last of the sugar has been added. Wile this final beating is happening add enough yellow colouring to the beating egg whites to achieve a egg yellow colour. Place the beaten egg whites into a large bowl and fold in the almond meal and icing sugar mixture a third at a time, remember this is not a pav so you don’t have to be really gentile. Continually mix the mixture until it resembles lava, it should be quite fluid and have a shiny surface. Lift the spatula out of the mixture, it should flow like thick pancake batter.
Set a fan forced oven to 140oC. Pipe the mixture into 4.5 to 5 cm rounds on greaseproof paper lined trays, I find using flat cookie trays the best as the don’t have a lip and allow the paper to remain flat. Ensure that you leave gaps between each macaron as they do spread. If you have mixed the mixture enough the piped macarons should be flat and round, if they have become miss shaped then the mixture has been over worked. Allow the piped macarons to sit for about an hour to develop a skin, you can test this by touching the macarons lightly, they should not leave any residue on your finger. Bake the macarons for 15 minutes or until they are cooked, test this by touching the top of the macrons, they should not wobble or move. Take the macarons out and allow to cool. Now this is when you can check if they have worked, they should have a shinny, smooth and slightly domed top with a wrinkly “foot” around the bottom edges, if they don’t resemble this then they have not worked properly and its back to the drawing board. Don’t be to disheartened if they don’t work they some time don’t work for me.
Wile the macarons cool you can begin on the lemon butter cream filling. Place caster sugar and the lemon juice in the pot and heat the sugar mixture on high heat until it reaches soft ball stage or about 120oC, use a candy thermometer for this. Wile the mixture is heating beat the egg yolk on high speed. When the sugar mixture has reached soft ball stage pour it into the beating egg yolks slowly, steam should billow out of the mixture. Let the mixture continue beating until it has cooled to about 30oC. Add the butter a little at a time to the cooled beating sugar egg yolk mixture, until all is completely combined. Add the lemon zest and lemon myrtle to the mixture. The butter cream should be thick, glossy and it should hold its shape.
When the macarons are cooled make matching pairs of macarons and lay them flat. Pipe the butter cream into one half of the paired macarons. Try not to add to much butter cream to each pair of macarons, or they will make a mess when you eat them later. Sandwich the two halves and place in an airtight container and refrigerate for two days, you can eat them the same day as you make them but they will be far better if left a few days.