Preheat oven to 180 degrees C. Wash ring tin in hot soapy water to ensure it is totally grease free. Let dry completely.
Sift the icing sugar and flour together and set aside.
In a large bowl, whisk the egg whites on high speed until foamy. Continue to whip on high speed while adding salt, cream of tartar, vanilla and almond essence until the whites have formed soft peaks. Gradually add the white sugar while continuing to whip until whites have stiff peaks. Quickly and gently fold in the flour mixture 1/4 cup at a time until flour is incorporated. Do not deflate egg whites.
Pour mixture into a ring tin. Sprinkle top with chopped almonds. Bake in preheated oven for 35 to 40 minutes, or until top of cake bounces back when lightly tapped. Balance the ring tin upside down on the top of a bottle, to prevent decompression while cooling. When cake is cool loosen sides with a long knife and invert onto a plate.