Preheat the oven to 350°F (175°C). Grease and flour a 9-inch round cake pan.
In a medium bowl, whisk together the flour, baking powder, baking soda, salt, and ground cinnamon. Set aside.
In a large bowl, beat the softened butter and granulated sugar together with an electric mixer on medium speed until light and fluffy, about 3 minutes.
Add the eggs one at a time, beating well after each addition.
Mix in the vanilla extract.
Add half of the dry ingredients to the butter mixture and mix on low speed until just combined.
Add the sour cream and mix until incorporated.
Add the remaining dry ingredients and mix until just combined. Do not overmix.
Fold in the chopped fresh apples gently with a spatula until evenly distributed.
Pour the batter into the prepared cake pan and smooth the top with a spatula.
Bake in the preheated oven for 45 to 50 minutes, or until a toothpick inserted into the center comes out clean.
Remove the cake from the oven and allow it to cool in the pan for 10 minutes.
Run a knife around the edges to loosen the cake, then invert onto a wire rack to cool completely before serving.