Meringues

Remove 1 oven tray and preheat the oven to 100 °C (210 °F).

Separate the 4 white from the egg yolks.
Put the whites in a rather large cul-de-poule.
Add 1 pinch of salt, and whisk the egg whites until they become very firm (slow beater at first and then faster and faster).
Add 250 g of icing sugar in a small amount while continuing to beat.

Unroll baking paper to the size of your tray, and "glue it" to the tray with 4 dots of egg white (used as glue).
Then, place on this paper small nuts of egg whites (possibly with a pastry bag). They should not touch each other.

Bake.

1 hour: white and mellow meringue.
1 hour 30 min: white and crisp meringue.
If the meringue becomes amber, it means that the oven is too hot.
(Above times may vary depending on your oven/meringue size. If necessary, try time / temperature variations).

When desired style is achieved, carefully remove the meringues right out of the oven.
Then store them in an airtight box (otherwise they would quickly soak humidity).

Meringues are a good way to use egg whites leftovers but takes time/energy. Recipe proposed here is for "French style". "Italian" one requests sugar to be cooked, "Swiss" on has egg white beaten while in a bain-marie.
Meringue might have been invented by Gasparini in Mehringhen, hence its name. Pastry bag & fancy tubes allow to make nice shapes. You can replace some icing sugar with granulated sugar.
Flavor meringues with crushed unsalted pistachios, or organic citrus zest (lemon kaffir lime…) before cooking. Use fresh egg whites, don't store until you used enough yolks. Once broken, egg degrade quickly.