Instructions

1. Preheat oven to 350 degrees F. Butter or spray an 8-inch round cake pan.
2. In a medium bowl, whisk together the flour, cinnamon and salt.
3. In the bowl of an electric mixer fitted with a paddle attachment, beat the 1/2 cup of sugar and melted butter until it has lightened.
4. Add the eggs, one at a time, beating between each addition and scraping down the bowl as needed.
5. Reduce the mixer speed to low and add the flour mixture alternately with the yogurt, beginning and ending with the flour. 
6. Stir in the sliced apples and the lemon zest, and pour the batter in the prepared pan.
7. Sprinkle the 1/3 cup sugar evenly over the top of the cake.
8. The original recipe suggests a baking time of 40 minutes, but mine takes an hour (until a tester inserted into the center comes out clean.
9. Let cool completely before serving.