Preheat the oven to 155'C.
Pass the almonds and icing sugar through a medium sieve to remove any lumps.
Whisk the egg whites with 150g of caster sugar. Whisk until you have a semi-stiff and glossy meringue.
Stir in one third of the dry ingredients. Once incorporated, repeat with the second third and then the final third. Add the food colouring and work the mixture with a spatula until it is smooth, shiny and a dropping consistency.
Fill a piping bag with the macaroon mix and pipe the macaroons onto a lined baking tray. Tap the tray on your work surface to smooth out the tops and remove any large air bubbles. Leave the macaroons to dry for 15 minutes at room temperature. They are ready to cook when the surface is touch-dry. Transfer to the oven and bake for 10-12 minutes. The macaroons are cooked when the top is firm. Remove from the oven and leave to cool for 10 minutes. After 10 minutes, lift the macaroons from the baking parchment and turn them over. Allow to cool thoroughly before filling.
Mix together the egg yolks, caster suger, elderflower cordial and the cornflour.
Place the milk and the lavender sugar in a saucepan and bring to the boil. Once boiling, pass the milk through a sieve and then add it, a little at a time, to the egg yolk mixture. Return to the pan and whisk over a medium high heat for 3-4 minutes, gently bringing the mixture back to the boil. Transfer the cream to a bowl and allow to cool. Once cool, place the elderflower and lavender cream in a piping bag.
Pipe the elderflower and lavender cream on to half of the macaroon shells. Top with a second macaroon shell to finish.
«Try making a simple elderflower cream and adding candied lemon and lime to your macaroons instead of using lavender.»