1. Draw a circle on a sheet of parchment paper or unglazed brown paper using the bottom of a 9-inch springform pan as a guide.
2. (Do not use recycled paper). Turn paper over onto baking sheet.
3. Beat egg whites in a large bowl at high speed with an electric mixer until foamy; sprinkle with cream of tartar and salt, and beat until soft peaks form.
4. Gradually add 1 cup sugar, bearing until stiff peaks form.
5. Fold in remaining 1/4 cup sugar, cocoa and cornstarch.
6. Pipe or spread mixture onto paper within the 9-inch circle.
7. Bake at 225 degrees for 15 minutes. Reduce heat to 200 degrees and bake 2 hours and 45 minutes or until firm and dry.
8. Let cool completely, and carefully remove from paper.