Preheat oven to 225°F.
Line a baking sheet with parchment paper.
In a clean mixing bowl, combine egg whites, cream of tartar, salt, vanilla flavoring, and food coloring if using.
Using a stand mixer or hand mixer, beat on low speed until frothy. Gradually increase speed to high.
Slowly drizzle in sugar over 2–3 minutes while continuing to beat. Beat until stiff, glossy peaks form.
Transfer meringue to a piping bag fitted with a round or star tip. Pipe heart shapes or small cookies onto prepared baking sheet.
Bake for 50–60 minutes. Avoid opening the oven door during baking.
Turn off oven and leave meringues inside for 1–2 hours to fully dry.
Meringues are done when they easily lift from parchment and feel completely dry.