Preheat oven to 350°F (175°C) and grease a 9x5-inch loaf pan with non-stick spray or butter.

In a medium bowl, toss the diced apples with brown sugar and cinnamon until evenly coated.

In a large mixing bowl, cream together the softened butter and granulated sugar until the mixture is light and fluffy.

Add the eggs one at a time, beating well after each addition, then stir in the vanilla extract.

In a separate bowl, whisk together the flour and baking powder.

Incorporate the dry ingredients into the wet mixture alternately with the milk, beginning and ending with the dry ingredients.

Spread half of the batter into the bottom of the prepared loaf pan.

Top with half of the prepared apple mixture, pressing it lightly into the batter.

Pour the remaining batter over the apples, followed by the remaining apple mixture.

Use a butter knife to gently swirl the apples into the batter for a marbled effect.

Bake for 55 to 65 minutes, or until a toothpick inserted into the center of the loaf comes out clean.

Allow the bread to cool in the pan for 15 minutes before transferring to a wire rack.

Whisk together the powdered sugar and caramel sauce until smooth, then drizzle over the cooled bread before slicing.