Preheat the oven to 350°F. Butter and flour a 9 inch round springform cake pan and line with a round of parchment paper in the bottom.
Zest the lemons and set aside. Peel the apples, cut into quarters and slice each quarter into thin slices, about ⅛ -¼ inch thick. Squeeze the lemon juice into the bowl with the apples, mix and set aside.
In a medium bowl combine the flour, baking powder and salt. Mix well and set aside.
In a stand mixer attached with the paddle attachment, cream the butter and the sugar until light and fluffy, about three minutes. You can also do this with a handheld mixer.
Beat in the eggs one at a time, scraping the bowl between each one.
With the mixer running at low speed, add the lemon zest and milk. Scrape down the sides of the bowl and mix for another minute on medium power.
Add half the flour mixture and mix gently. Add the second half and mix until just combined.
Fold in about half the apples and all the juices by hand and spread into the bottom of the prepared pan.
Gently arrange the remaining apples on top of the cake in a round fan with an outer and inner circle, as shown in the pictures.
Bake the cake for 50-60 minutes or until a toothpick comes out clean when tested in the center of the cake. Let cool for at least 30 minutes before removing the sides of the springform pan. Continue to cool completely on a cooling rack.