Preheat your oven to 350°F (175°C). Grease and flour a 9×9-inch baking pan or a similar-sized baking dish.

In a bowl, whisk together the all-purpose flour, ground cinnamon, ground nutmeg, baking soda, and salt. Set this mixture aside.

In a large mixing bowl, beat the softened unsalted butter and granulated sugar until the mixture becomes light and fluffy, usually for about 2-3 minutes.

Beat in the eggs, one at a time, ensuring they are well incorporated. Stir in the pure vanilla extract.

Gradually add the dry ingredient mixture to the butter and sugar mixture, alternating with the sour cream. Begin and end with the dry ingredients. Mix until just combined.

Gently fold in the peeled, cored, and chopped apples.

In a small bowl, mix the granulated sugar and ground cinnamon for the topping.

Spread half of the cake batter into the prepared baking pan.

Sprinkle half of the cinnamon sugar topping over the batter.

Add the remaining cake batter and smooth it out.

Sprinkle the rest of the cinnamon sugar topping over the top.

Bake the cake in the preheated oven for approximately 45-50 minutes, or until a toothpick inserted into the center comes out clean.

Allow the cake to cool for a while before serving. You can enjoy it warm or at room temperature.