|2||egg whites, at room temperature|
|1/8||teaspoon cream of tartar|
|pinch of salt|
|¾||teaspoon cocoa for dusting|
Beat egg whites and cream of tartar on high speed with an electric mixer until soft peaks form. Add salt and continue beating, while gradually adding sugar, until stiff peaks form and surface appears glossy.
Transfer egg whites to a pastry bag fitted with a large plain tube (ATECO #8). On an ungreased cookie sheet, pipe mushroom stems about 1 1/ 4-inches high, and pipe domes of meringue approximately 1 1/ 2-inches wide for mushroom caps. Using a fine mesh strainer, dust mushroom caps with cocoa. Bake at 200 degrees for 1 ½ hours, until meringues are very dry, but not brown. Remove meringues to a rack to cool.
When cool, slice pointed tip from mushroom stems with a sharp knife. Spread chocolate or mocha buttercream on bottom of caps. Attach stems and set aside to dry. Store mushrooms in an airtight container for up to 2 weeks.
Recipe makes 16-18 mushrooms.