Preheat the oven to 350°F (175°C). Grease a 9-inch round cake pan and set aside.

Peel the apples, core them, and slice into thin wedges or half-moons. Set the slices aside.

In a large mixing bowl, combine the granulated sugar, melted butter, and eggs. Beat until smooth and slightly glossy. Stir in the vanilla.

In a separate bowl, whisk together the flour, baking powder, cinnamon, and salt.

Gradually add the dry mixture to the wet ingredients, stirring until just combined; avoid overmixing.

Fold the sliced apples into the batter so they’re evenly distributed.

Pour the batter into the prepared pan and spread it evenly with a spatula. Arrange a few extra apple slices on top if desired.

Bake for 45–50 minutes, until the top is golden and a toothpick inserted into the center comes out clean or with a few moist crumbs.

Cool the cake in the pan for 10–15 minutes, then transfer to a wire rack to cool completely before slicing.