Preheat your oven to 350°F (175°C). Grease a 9-inch cake pan and set aside.
Combine the dry ingredients: whisk together the flour, baking powder, salt, ground cinnamon, and ground cardamom in a large mixing bowl until well blended.
In another bowl, beat the eggs with the sugar until the mixture is smooth and slightly pale, about 2 minutes.
Stir in the melted butter and milk into the egg mixture until combined and creamy.
Gradually fold the dry ingredients into the wet mixture, mixing gently until just blended and smooth.
Spread the batter evenly into the prepared cake pan, smoothing the top with a spatula.
Arrange the thinly sliced apples in a decorative pattern on top of the batter, fanning them out evenly across the surface.
Bake in the preheated oven for about 40 minutes, or until the top is golden and a toothpick inserted into the center comes out clean.
Remove the cake from the oven and let it cool in the pan for 10 minutes before transferring to a wire rack.
Once cooled, sprinkle the cinnamon sugar evenly over the top of the cake for a sweet, crunchy glaze.
Slice and serve the cake, enjoying its tender crumb, fragrant spices, and the contrast of crisp apple edges with a dusting of sweet cinnamon sugar.