Preheat oven to 350 degrees F and spray 2 loaf pans with non-stick cooking spray
In a large bowl, peel and chop the apples
Mix brown sugar and 2 tsp cinnamon in a small bowl and set aside
Mix 4 tbsp sugar and remaining 2 tsp cinnamon with the chopped apples
In another large bowl, beat butter and 1 1/3 cup sugar until soft. Add eggs one at a time, then add vanilla, mix until combined
In another bowl, mix flour salt and baking powder together, then add to the creamed butter mixture and beat until combined
Mix in the milk until combined
Pour 1/4 of the batter into the bottom of each of the loaf pans
Spoon half of the apples into each of the loaf pans
Sprinkle 1/4 of the brown sugar/cinnamon mixture on top of the apples
Pour the remaining batter on top of each loaf pan and then sprinkle with the remaining brown sugar/cinnamon mixture
Bake at 350 for 45 minutes, or until a toothpick comes out clean