In a small pot over low heat, combine sugar and water. Swirl the pot over the burner to dissolve the sugar completely. Do not stir. Increase the heat and boil the syrup to soft-ball stage (115-118ºC). A candy thermometer is best used for its accuracy.
Note: If you do not have a candy/sugar thermometer, you can determine the soft ball stage syrup by dropping a small amount of sugar syrup into very iced cold water, it shall then form a ball that does not hold its shape when pressed with your fingers.
Wash down the inside wall of the pot with a wet pastry brush to help prevent sugar crystals from forming around the sides.
When the temperature of the sugar syrup is around 90°C, start beating the egg whites in your mixer on medium low speed until foamy, while focusing on the temperature of the sugar syrup as you're aiming for 115-118ºC. Continue to beat on medium speed until you achieve soft peak consistency.
Once the right temperature is reached, pour the hot sugar syrup in a thin stream over egg whites with the mixer running over medium high speed. Continue to beat until the egg whites are stiff, thick and glossy. Allow the mixer to beat the meringue for about 7- 10 minutes until cool.
While waiting for your meringue to cool, we now proceed to the Almond Paste.
In a separate bowl, combine the remaining 90g of egg whites with icing sugar, ground almond and mix well.
Once the meringue is ready, fold into the almond/sugar mixture with a rubber spatula. You should fold until it is mixed well or just barely uniform by using as few strokes as possible. It is extremely important that you do not over mix the batter as it will thin down or become runny.
Your batter is considered perfectly done when you are able to lift your spatula and a thick trail of ribbon slowly cascades off, back into the bowl.
Divide the batter into three potions for different colours. Add few drops of food colouring of your choice and mix well.
Now you're ready to fill up your piping bag. If the mixture is just right, it will ooze from the tip slowly under its own weight using round tip nozzle.
Place the baking parchment sheets on two baking trays. Trays should be placed one on top of the other so that the macarons do not get burned easily. Then, start piping 2cm macarons onto your baking parchment sheets, spacing them a few centimetres apart.
Once you complete a full pan, tap your baking tray gently, to break unwanted air bubbles and allow the macarons to rest for 20 - 30 minutes. (They can sit longer if you want to bake one or two sheets at a time, to develop slightly thicker shells and nice distinctive 'feet' on the edge of the shells).
Bake at 150°C for 15 minutes. Remove from the oven and let the macarons sit on the parchments or baking mats for 15-20 minutes to further dry up the bottom of the macarons before removing them.
On the choice of fillings for macarons, you have a wide variety to choose from. Since macarons are sweet enough on their own, try to neutralise the sweetness by using lemon or orange buttercream. Cherries and berries are another ideal alternative. For chocolate lovers, use chocolate ganache which is heavenly and gives a bittersweetness to the macarons.