Thoroughly clean your mixing bowl, whisk attachment and any other dishes that will touch the egg whites, before you begin. You can use a splash of white vinegar or lemon juice.
Very carefully separate the eggs into egg whites and yolks. Not a drop of water, fat or yolk should get into the egg whites.
Weighing the egg whites and take twice as much sugar.
Use a few drops of lemon juice, vinegar, or a pinch of cream of tartar to helps lower the ph and in turn strengthen the proteins and creates a more stable meringue.
Start by whisking the egg whites on the low speed. When the white foam begins to appear, the mixer speed can be gradually increased.
When the egg whites are beaten to soft picks, increase the mixer speed to medium high and add the sugar in slowly. I add about 1 tablespoon at a time and wait about 20-30 seconds before the next addition. Not rushing this process is key to making the mixture stable.
After the sugar is all in, you need to whisk the meringue for another 4-5 minutes on high speed, so that the mixture becomes smooth, glossy, has a very stiff texture and the powder sugar has completely dissolved. Which you can check by rubbing a bit of the meringue between your fingers to make sure there are no undissolved sugar crystals left. The meringue should not feel gritty. If the meringue feels grainy, mix a few minutes more.