Preheat the oven to 350°F (175°C). Grease and flour an 8-inch (20 cm) round cake pan.
In a small bowl, toss the sliced apples with lemon juice to prevent browning. Set aside.
In a medium bowl, whisk together the all-purpose flour, baking powder, baking soda, ground cinnamon, and salt until well combined.
In a large bowl, beat the granulated sugar and eggs together until the mixture is pale and slightly thickened, about 2-3 minutes.
Add the vegetable oil, milk, and vanilla extract to the egg mixture and mix until fully incorporated.
Gradually add the dry ingredients to the wet ingredients, folding gently with a spatula until just combined. Do not overmix.
Pour half of the batter into the prepared cake pan and spread evenly.
Arrange half of the apple slices evenly over the batter layer.
Pour the remaining batter over the apple slices and spread gently to cover.
Top the cake with the remaining apple slices, arranging them neatly.
Bake in the preheated oven for 35-40 minutes, or until 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.
Transfer the cake to a wire rack and cool completely before slicing and serving.