Preheat the Oven and Prepare the Pan:
Preheat your oven to 350°F (175°C). Line a loaf pan with parchment paper or grease it well with non-stick spray.
Make the Cinnamon Sugar Mixture:
In a small bowl, mix the brown sugar and cinnamon. Set aside.
Prepare the Apples:
Peel, core, and chop the apples into small pieces. Toss them lightly in 1 tablespoon of the cinnamon sugar mixture.
Cream Butter and Sugar:
In a large mixing bowl, beat the granulated sugar and softened butter until light and fluffy. Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.
Combine Dry and Wet Ingredients:
In a separate bowl, whisk together the flour and baking powder. Gradually add the dry ingredients to the butter mixture, alternating with the milk, beginning and ending with the dry ingredients. Mix until just combined.
Assemble the Bread:
Pour half of the batter into the prepared loaf pan. Sprinkle half of the cinnamon sugar mixture over the batter, followed by half of the chopped apples. Spread the remaining batter on top and repeat with the remaining cinnamon sugar and apples. Lightly swirl the cinnamon sugar and apples into the batter with a knife.
Bake:
Bake for 50–60 minutes, or until a toothpick inserted into the center comes out clean. If the top starts to brown too quickly, loosely tent the bread with foil.
Cool the Bread:
Let the bread cool in the pan for about 15 minutes before transferring it to a cooling rack to cool completely.
Prepare the Glaze:
In a small bowl, mix powdered sugar and milk until smooth. Drizzle over the cooled bread.
Serve and Enjoy:
Slice and serve as is or with a pat of butter for extra indulgence.