Daffodil Cake Recipe

This is an Australian/ New Zealand recipe. Not yet baked in my kitchen but perhaps someone would like to try it?
It is a delicate sponge cake, lightly flavoured with orange and with swirls of yellow and white in every slice.  It is made in a 28cm or 30cm ring tin. 
It is reputed to have just one gram of fat per serving so not too much fat if you are tempted by another slice?
Preparation time 20 minutes. Cooking time 35 minutes. Ready within an hour.

Ingredients: Serves: 16
4 large eggs, separated
1 1/2 cups caster sugar
2 teaspoons grated orange rind
1 tablespoon vanilla essence
6 large egg whites
1 teaspoon cream of tartar
1 1/3 cups plain flour, sifted
1/3 cup icing sugar, sifted, to decorate

Prep: 20 minutes | Cook: 35 minutes
1. Preheat the oven to 190°C.
2. Place the egg yolks, 1/4 cup sugar and orange rind in a large bowl.
Beat with an electric mixer at high speed until the mixture is thick and lemon-coloured, about 10 minutes.
Add the vanilla and beat to combine.
3. Place the egg whites in a separate large bowl and beat with clean beaters at high speed until foamy.
Add the cream of tartar and beat until soft peaks form.
Add the remaining sugar, 2 tablespoons at a time, and beat until the sugar dissolves and stiff, glossy peaks form.
4. Sift 1/3 cup flour over the egg whites and gently fold in with a whisk just until the flour is no longer visible.
Repeat three times until all the flour is used.
Spoon one-third of the egg white mixture into the yolk mixture and gently fold in.
5. Spoon heaped tablespoons of the yellow and white mixtures by turns into a 28cm or 30cm ring tin.
Swirl a thin spatula or knife through the mixture to give a marbled effect. Lightly swirl the top of the cake, too.
Bake until the cake springs back when lightly touched, about 35 minutes.
6. Leaving the cake in the tin, invert it and place over the neck of a bottle to cool completely. (Cooling the cake in the tin the right way up will cause it to sink.)
Run a knife around the cake to loosen it. Turn it out onto a plate and dust with icing sugar.

[I think I would be tempted to make a light orange flavoured icing to dribble around the ring cake and decorate it with yellow and white sugar flowers]