Pre heat your oven to 350 degrees.

In a food processor, combine the walnuts and the confectioner's sugar and process until you have a fine powder. (I like to leave mine a little coarse.)

Combine the walnut powder with the flour, the salt and the baking powder. Reserve.

Beat the egg yolks - either using your hands or a mixer - and slowly add the walnut oil, like you would do when making mayonnaise. Once emulsified, add the yogurt and mix until incorporated.

Using a mixer, whisk the egg whites until foamy. Add the sugar and keep whisking until soft peaks form. Reserve.

Add the egg yolk/oil mixture to the dry ingredients and stir until well combined.

Fold the whites gently, mixing with a wooden spoon or spatula until you don't see any more whites.

Butter and flour a cake pan (I use a 9X5 loaf pan) and pour the batter into the pan.

Bake for 35 to 45 minutes or until the cake is set and a tooth pick or cake tester inserted in the cake comes out clean.

Let the cake cool for at least 10 minutes before removing from the pan.

Serve while it's still warm! :)