1. Preheat oven to 325°F. Have ready a 9-inch springform pan; do not grease it.

2. Sift cake meal with potato starch into a bowl. Beat egg yolks in a large bowl with an electric mixer. Beat in ½ cup sugar. Whip at high speed about 5 minutes or until mixture is pale and very thick. Stir in lemon juice and zest.

3. In another large clean bowl, beat egg whites and salt with a mixer until soft peaks form. Gradually beat in remaining ¼ cup sugar. Beat at high speed until whites are stiff and shiny but not dry.

4. Fold cake meal mixture into yolks. Lightly fold in whites in 3 batches, just until batter is blended.

5. Lightly spoon about one third of the batter in prepared pan. Gently cover with half the apples. Sprinkle them with 2½ teaspoons cinnamon mixture. Top with half the remaining batter, then with the remaining apples, and sprinkle them with the remaining cinnamon mixture. Spoon remaining batter over apples and spread gently.

6. Bake about 1 hour or until top is firm and a cake tester inserted in cake’s center comes out clean. Cool in pan on a rack 10 minutes. Run a metal spatula carefully around cake. Remove sides of pan. Cool completely. (Cake can be kept, covered, 2 days in refrigerator.)