1) Preheat the oven to 325°F.
2) To make the cake: Combine the flour, 1/2 cup of the sugar, and the orange zest. Set aside.
3) In a large mixing bowl, combine the egg whites, salt, and extract. Beat until the mixture is frothy.
4) Sprinkle the cream of tartar on top and continue beating until stiff, glossy peaks form.
5) Slowly pour in the remaining 1/4 cup sugar while beating, then gradually fold in the dry ingredients.
6) Transfer the batter to the ungreased cups of a mini angel food cake pan; a piping bag works well here.
7) Bake the cakes for 20 to 22 minutes, or until the tops are golden brown and spring back when lightly touched.
8) Remove the pan from the oven, and place it upside down on a cooling rack. Let the cakes cool for 1 hour in the pan.
9) Loosen the edges of the cakes, and remove them from the pan.
10) To make the glaze: Stir the ingredients together until the mixture is smooth and pourable. Pour the glaze over the tops of the cakes.
Yield: 6 individual cakes.