Weigh the egg whites. The weight of the other macaron ingredients will be calculated based on that. Measure carefully.
Beat the egg whites with a handheld mixer to turn it into meringue. Add the granulated sugar to it in 2 batches as you whip it.
Sift the almond flour and powdered sugar together twice. Add the meringue to this in 3 batches, folding it in.
Use a cut and fold motion, stirring up from the bottom. Don't crush the air bubbles or beat the mixture too much. It's similar to when you stir up freshly cooked rice.
When everything is mixed, add the vanilla essence. Then perform the macaronage (a procedure used to make macarons): Lift the mixture up from the bottom of the bowl with your spatula, and then stroke the surface. Repeat several times.
When the batter forms a thick ribbon that falls slowly from the spatula, it's done. It can be a bit puffy still.
Make a piping bag ready by folding back the edge and standing it up in a cup. Transfer the macaron batter to the piping bag.
Pipe the batter out onto a kitchen parchment paper lined baking sheet. Aim to make each round 3 cm in diameter.
Gently put the dragées on top of the macarons, then push them in very lightly with the blunt end of a toothpick.
Leave the macarons until the surface has dried completely. This will take 1 to 5 hours, depending on the humidity.
Bake in a 180°C oven for 3 to 5 minutes. The pieds (the 'feet' of a macaron, or the frilly parts around the perimeter) will start to form.
Take the macarons out, set the oven to 120 to 130°C, and bake for another 10 to 15 minutes. If it looks like the macarons are turning brown, turn the temperature down.
Let the macarons cool down completely. Cut the kitchen parchment paper apart with the macarons are still stuck to it, so that each macaron is separate.
Put the macarons carefully into a plastic bag, and refrigerator for a day.
Make the buttercream: Have the butter at room temperature.
Beat the egg white. Add the granulated sugar to it in 2 batches as you beat it.
When the meringue is done, add the powdered sugar to it in 3 batches while beating at low speed.
Add the butter in 3 batches while beating at low speed.
Add the vanilla essence and food coloring, and keep beating at low speed.
To finish: Gently peel the paper off the macarons. If they are uneven in size, line them in order from large to small, and pair up the ones that are of similar size.
Fit a round tip on a piping bag, fill the bag with buttercream and pie the filling between the macarons.
Put the macarons back in the plastic bag. Rest in the refrigerator overnight and they're done.