Preheat oven to 225°.
Line 2 baking sheets with parchment paper; set aside.
Place first 3 ingredients in a large bowl, and beat with a mixer at high speed until foamy. Add sugar, 1 tablespoon at a time, beating until stiff peaks form. Beat for 1 minute at high speed or until mixture is shiny. Gently fold in chocolate.
Spoon mixture into a large zip-top plastic bag. Snip a 1/4-inch hole in 1 bottom corner of bag. Pipe 24 (4-inch-long) zigzag shapes onto each prepared pan.
Bake at 225° for 30 minutes with 1 pan on bottom rack and 1 pan on second rack from top. Rotate pans; bake an additional 30 minutes or until dry to the touch. Cool on pans 30 minutes on wire racks. Carefully remove meringues from paper; cool completely on wire racks.
Note: Store meringues in an airtight container at room temperature for up to two weeks.