Preheat oven to 350°F (175°C). Line a 9x5 or 8x4 inch loaf pan with parchment paper with an overhang on all sides to easily lift the bread out of the pan after baking. Set aside.
Combine 2 tablespoon white sugar and 1 teaspoon cinnamon in a small bowl. Set aside. Combine flour, baking powder, salt, and cinnamon in a small bowl. Set aside.
In a large mixing bowl, using a handheld or stand mixer fitted with a paddle or whisk attachment, mix applesauce and brown sugar just until combined for about 1 minute. Turning mixer to low, slowly mix in oil to combine. Add eggs and vanilla* and stir just until combined for about 1 minute. Add flour mixture and stir to combine. Don't overmix at any step.
Fold in chopped apples just until combined. Transfer batter to prepared loaf pan and top with cinnamon sugar mixture and additional apple slices if desired. Bake for about 55-60 minutes or until a toothpick in the center comes out clean. Let cool in the pan for 30 minutes. Then transfer to a wire rack and let cool completely. Store in an airtight container at room temperature for up to 2 days.