Heat the oven to 180°C / 350°F. Grease and line a 22 cm / 9 in round cake pan.
Peel the apples, remove the cores, and slice them very thinly so they soften evenly while baking.
Place the sliced apples in a bowl with half the cinnamon and the lemon zest. Toss gently and set aside.
In a large bowl, beat the eggs with the sugar for 3 to 4 minutes until lighter, smoother, and slightly fluffy.
Add the melted butter, milk, and vanilla extract. Mix until fully combined.
Sift in the flour, baking powder, salt, and remaining cinnamon. Stir gently just until no dry flour remains. Do not overmix.
Fold about two-thirds of the apple slices into the batter so every spoonful gets fruit.
Pour the batter into the prepared pan and smooth the top with a spatula.
Arrange the remaining apple slices over the surface in overlapping circles for an elegant finish.
Bake for 45 to 55 minutes, until golden and a skewer inserted in the center comes out clean or with a few moist crumbs.
Let the cake rest in the pan for 15 minutes, then transfer it to a rack to cool until warm or room temperature.
Dust with powdered sugar before serving.
Dish type
Rustic Italian dessert cake