Preheat an oven to 375 degrees F (190 degrees C). Grease an 8-inch square pan.
Combine matzo meal, cinnamon sugar, and salt in a large bowl. Beat in egg yolks, peanut oil, lemon juice, and lemon zest. Fold in the egg whites. Pour half of the batter into the prepared pan. Cover the batter with apple slices, then pour the remaining batter on top.
Bake in the preheated oven until a toothpick inserted into the center comes out clean, about 45 minutes. Cool in the pans for 10 minutes before removing to cool completely on a wire rack.