Preheat the oven to 356°F (180°C). Grease and flour a 9-inch (22 cm) round baking pan.
Peel, core, and thinly slice the apples. Toss them with lemon juice to prevent browning.
In a large bowl, beat the eggs, sugar, lemon zest, and a pinch of salt with a hand mixer until thick and creamy (about 5 minutes).
Gently mix in the dry ingredients and milk until just combined.
Fold two-thirds of the apples into the batter.
Pour the mixture into the prepared pan and arrange the remaining apple slices, flat-side down, on top.Sprinkle with sugar (optional).
Bake for 35 minutes, or until a toothpick comes out clean and the top is golden brown.
Let the cake cool completely on a wire rack. Dust with powdered sugar just before serving.
