Preheat Oven:
Preheat oven to 350°F (175°C). Grease and flour a 9-inch round or square baking pan.

Mix Dry Ingredients:
In a medium bowl, whisk together flour, baking powder, baking soda, cinnamon, and salt.

Cream Butter and Sugar:
In a large bowl, beat butter and sugar until light and fluffy. Add eggs one at a time, beating well after each. Stir in vanilla extract.

Combine Ingredients:
Alternately add dry ingredients and sour cream to the butter mixture, beginning and ending with dry ingredients. Fold in diced apples.

Bake:
Pour batter into prepared pan and bake for 40–45 minutes, or until a toothpick inserted in the center comes out clean.

Cool and Serve:
Allow cake to cool before slicing. Enjoy as is or with a dusting of powdered sugar or a scoop of vanilla ice cream!