1/2 cup butter
1 cup granulated sugar
1 egg plus 1 egg yolk
1 1/2 cups flour
1 teaspoon baking powder
1/2 teaspoon salt
1/4 cup fresh lime juice
1 1/2 teaspoons grated lime peel (green part only)
1/2 cup confectioners' sugar

Preheat oven to 350 degrees F. Spray baking sheets with nonstick vegetable coating.

In a large bowl, mix butter, sugar, egg and egg yolk until creamy. Thoroughly mix in flour, baking powder, salt, lime juice and lime peel. Spray cookie sheet with nonstick vegetable coating. Form dough into 1/2-inch balls. Place on prepared cookie sheet and bake until lightly browned, 8 to 10 minutes. Remove to wire rack. While still warm, sift confectioners' sugar over cookies.