Preheat the oven: Preheat your oven to 350°F (175°C). Grease a 9×5-inch loaf pan or line it with parchment paper for easy removal.
- Prepare the dry ingredients: In a medium bowl, whisk together the flour, baking soda, cinnamon, and salt. Set aside.
- Mix the wet ingredients: In a large mixing bowl, whisk together the granulated sugar, brown sugar, oil (or melted butter), eggs, and vanilla extract until smooth and well combined.
- Add the wet and dry ingredients: Gradually add the dry ingredients to the wet mixture, alternating with the buttermilk, beginning and ending with the dry ingredients. Stir gently until just combined.
- Fold in the apples and nuts: Gently fold the chopped apples and optional nuts into the batter until evenly distributed.
- Prepare the topping (optional): In a small bowl, mix together the cinnamon and sugar for the topping. Sprinkle evenly over the batter in the loaf pan.
- Bake the bread: Pour the batter into the prepared loaf pan and smooth the top. Bake for 55-60 minutes, or until a toothpick inserted into the center comes out clean.
- Cool and serve: Let the bread cool in the pan for about 10 minutes, then transfer it to a wire rack to cool completely before slicing.