Baked French meringue cookies (also referred to as meringue kisses) are super simple to make with just 2 ingredients. Though they look beautiful when piped, you can easily use a spoon to make free-form cookies, as well.
Preheat oven to 90°C/200°F. In a large bowl or the bowl of a stand mixer fitted with a whisk attachment, add the egg whites and the vinegar, if using. Using a hand mixer or a stand mixer, start on low speed and then increase until the egg whites are lightly foamy and reach very soft peaks (see note 2).
Increase the mixer speed and, one tablespoon at a time, slowly add the sugar, ensuring that each addition is incorporated before adding the next. Continue whipping the meringue once all of the sugar is added until it is very glossy, there is no graininess when touched and the mixture holds a stiff peak (see note 3).
On two rimmed baking sheets, dab a small amount of meringue onto the corners and then press some parchment paper over the meringue, the meringue serving as a glue for the parchment. Transfer the meringue to a piping bag (or use a spoon) and pipe 18 kisses across the 2 baking sheets.
Move the meringues to the oven - you may position the trays on 2 racks - and bake until dried and crisp - about 2 hours. Turn off the heat but leave the meringues in the oven as it cools down. Once completely cool, the meringues are ready to eat.
Video
Notes
I recommend using caster sugar (also known as superfine sugar) over granulated as the finer texture dissolves more quickly in the egg whites. However, if all you have is granulated sugar, this will work just fine. Just ensure that there is no grainy texture in the merinque before baking.
A soft peak means that, when the whisk is lifted, the point droops slightly into itself.
A stiff peak means that, when the whisk is lifted, the point stays upright and stable.