Preheat the oven to 250F and line a large sheet pan with parchment paper or a Silpat mat.
Add the egg whites to the bowl of a stand mixer fitted with the whisk attachment. Beat on medium-high speed until the egg whites start to become frothy.
Add the cream of tartar, if using.
Add the caster sugar a little bit at a time with the mixer on medium-high speed until the meringue is close to forming stiff peaks.
Add the vanilla extract and beat until the meringue forms stiff peaks.
If desired, transfer half of the mixture to a separate bowl and gently fold in pink or red gel food coloring. Be very gentle, making sure to not deflate the egg whites!
Carefully transfer the mixture to a piping bag fitted with a large star, large round, or large open star attachments. Pipe small dollops (about 1” in diameter) that are at least 1″ inch apart.
Bake the meringues for exactly one hour, and then turn off the oven and slightly open the oven door but leave the meringues inside! Allow them to slowly cool to room temperature inside the warm but cooling oven.
Store in an airtight container for up to 1 week at room temperature.