Spray a baking sheet with nonstick spray; set baking sheet aside.
In a medium saucepan combine the water and margarine. Bring to boiling. Add the flour all at once, stirring vigorously. Cook and stir until mixture forms a ball that does not separate. Remove from heat. Cool for 10 minutes. Add the egg whites and the whole eggs, one at a time, beating with a wooden spoon after each addition until smooth. Spoon batter into a decorating bag fitted with a number 10 or larger tip. Pipe batter into twelve 4x3/4x1-inch strips, about 3 inches apart, onto the prepared baking sheet.
Bake in a 400 degree F oven about 35 minutes or until golden and firm. Remove from baking sheet; cool on a wire rack.
Meanwhile, for the mint sauce, in a small saucepan combine sugar, cocoa power, and cornstarch. Stir in evaporated skim milk. Cook and stir over medium heat until sauce is thickened and bubbly. Cook and stir for 2 minutes more. Remove from heat. Stir in peppermint extract. Cool sauce slightly before serving.
Split the eclairs and remove any soft dough from inside. Fill each eclair with frozen yogurt. If desired, lightly sift powdered sugar over eclairs. Serve with Chocolate-Mint Sauce. Makes 12 servings.