Preheat the oven to 155'C.
Sift the ground almonds and the icing sugar together.
Whisk the egg whites until white and fluffy and then add the caster sugar to the egg whites and continue whisking until you have stiff, glossy peaks.
Fold the ground almonds and icing sugar into the meringue mixture.
Cut and fold the mixture with a spatula until all of the dry ingredients are incorporated and the mixture is smooth, shiny and has reached the ribbon stage.
Carefully add the food colouring making sure not to overwork the mixture. Spoon the mixture into a piping bag.
Pipe 2cm circles in straight lines across a baking sheet lined with a silicon paper. Leave a 1 cm gap between each macaroon shell. Drop the tray of macaroons onto the work surface from about 30 cm to remove any large air bubbles.
Allow the macaroons to rest at room temperature for 20 minutes or until the macaroon shells are no longer sticky to touch.
Bake in the oven for 15 minutes. If you are baking lots of macaroons you may need to keep the oven door slightly ajar (with a spoon or paper) to prevent steam building up in the oven. After 15 minutes, check the macaroons are cooked by gently lifting a macaroon at the edge of a tray. If the test macaroon does not stick, allow the tray of macaroons to finish cooking on the tray as it cools.
Allow the macaroons to cool completely before filling.
In a mixing bowl, whisk together the egg yolk, sugar, corn starch and a spoonful of the Lactofree milk.
Meanwhile, bring the remaining Lactofree milk and the Matcha tea powder up to the boil, making sure to whisk out any lumps. Mix this liquid into the egg yolks whilst continually whisking.
Return the liquid to the pan and cook over a low heat until the cream is thick. Remove form the heat and allow to cool slightly.
Whisk in the Lactofree spread little by little, until it is all incorporated and the pastry cream is glossy.
Transfer to a shallow dish, cover with cling film making sure the cling film is in touch with the surface of the pastry cream. Refrifgerate until cold.
When cold, beat the custard until soft and spoon the cooled filling into a piping bag and then pipe on to the centre of half of the macaroon shells. Top with a second macaroon shell and twist gently to spread the mixture to the edges.
«It is very important that the mixture is cool before you pipe it onto the macaroons. If the mixture is hot then the macaroons will become soggy.»