Preheat oven 150C/ 300F/ GM2 and line 4 baking sheets with baking parchment (insert a template underneath if using or draw small circles (approx 3cm in diameter) onto the baking parchment and flip it over so the pencil/ ink is on the reverse). The macarons can be spaced 1.5 cm apart as they do not spread during cooking.
Measure the egg whites (it's really important to be precise on your weights in this recipe so I recommend using digital scales) into a medium mixing bowl and sprinkle over the saffron (if using). Let sit for 10 minutes
If using blanched almonds grind in a processor (or coffee grinder) until fine
Mix the ground almonds with the icing sugar and sieve into a medium sized mixing bowl. Set aside
Begin to whisk the egg whites, using electric beaters until at the soft peak stage
Add the caster sugar, a dessert spoon at a time, beating well between each addition
When the meringue is glossy and the egg white is fully incorporated add the gel (if using) a little at a time and beat well to ensure the colour is evenly distributed
Add the meringue to the icing sugar and almonds and fold it in using a rubber spatula, taking care to ensure ingredients from the sides and bottom are incorporated. The aim is to knock some air out of the mixture, but not too much - so go steady - not ultra gentle and not ultra rough
After 25 folds the batter will be approaching it's ideal state. Lift the spatula out and let a little mixture drop back into the bowl - it should fall in ribbons over the surface and blend back in after about 20 seconds. If it doesn't blend back in on it's own give the mix a couple more turns with the spatula and reassess. Keep doing this until the ideal state is reached - it should remind you of lava. If your mix is too thick your macaroons will not have a smooth top. If it is too runny, they will spread too far and be flat. Take your time and go steady with the folding until the batter blends back into itself after 20 seconds. If you go too fast and end up with runny batter it cannot be salvaged. Aim
Once the batter is ready spoon it into a piping bag fitted with a plain round tip approx 1cm in diameter (I used a Wilton 1A). Pipe circles approx 3cm in diameter onto the baking parchment (don't forget - a template or circles drawn on will help you achieve uniform sized macaron shells).
Pick up the baking tin and tap it lightly on your work surface to help eliminate any points that may have formed on the shells. Remove the templates (if used) by carefully lifting up an edge of baking parchment and sliding it out. Let the macaron shells rest for 30 minutes to form a tacky skin
Transfer to the oven and back for approx 18 minute. Open the oven door briefly after 5 minutes and again 5 minutes later to let out steam
After 18 minutes try to carefully lift one of the macarons off the baking sheet. If it comes off cleanly, the macarons are fully cooked and can be removed from the oven. If you feel resistance, return the macarons to the oven for a further 2 minutes and test again
When out of the oven, slide the macarons (on their parchment) off the baking sheets, to prevent further cooking and allow to cool on a work surface
Once completely cool, gently peel them off the baking parchment and sandwich the macarons together using the orange thyme butter. For a professional look pipe a large tespoonful (12-15g) into the centre of one shell, then top with another shell
Rest in the fridge overnight and allow to come back to room temperature before serving. The macarons must rest for 12 hours to ensure that the trademark macaron texture (crisp on the outside, yet soft in the middle) is achived
Store the macarons, refrigerated, for up to 1 week