Peel, core, and chop apples into small cubes. Toss with lemon juice and set aside.
Preheat oven to 350°F (175°C). Grease and line your cake pan.
In a large bowl, whisk flour, baking powder, baking soda, salt, and cinnamon.
In another bowl, beat butter with granulated and brown sugar until light and fluffy.
Add eggs one at a time, then mix in vanilla extract.
Stir in sour cream or yogurt until smooth.
Gradually fold dry ingredients into wet ingredients.
Gently fold in apples and optional nuts or raisins.
Transfer batter to prepared pan. Sprinkle with cinnamon sugar if desired.
Bake for 45–55 minutes, or until a toothpick comes out clean. (For loaf pan, add 5–10 minutes.)
Cool for 10 minutes before removing from the pan. Let cool completely before slicing.