Preheat oven to 350°F (175°C) and grease or line a loaf pan.
In a bowl, mix flour, sugar, cinnamon, baking soda, and salt.
In another bowl, whisk oil, eggs, vanilla, and milk or yogurt.
Combine wet ingredients with dry ingredients and mix gently until just combined.
Fold in chopped apples and optional nuts.
Pour batter into the prepared loaf pan and spread evenly.
Sprinkle brown sugar on top if using.
Bake for 50–60 minutes until a toothpick inserted comes out clean.
Cool for 10–15 minutes before slicing and serving