Beat first 4 ingredients at high speed with an electric mixer until foamy.
Add sugar, 1 tablespoon at a time, beating until stiff peaks form and sugar dissolves.
Spoon mixture into 36 (1 1/4-inch) mounds onto parchment paper-lined baking sheets.
Bake at 200° for 2 hours; turn oven off. Let meringues stand in closed oven with light on for 8 hours.