Preheat & Prep: Preheat oven to 350°F (175°C) and grease a loaf pan. Line with parchment paper for easy removal.
Make Cinnamon Sugar & Apples: Mix brown sugar and 1 teaspoon cinnamon. In another bowl, toss chopped apples with 2 tablespoons sugar and remaining cinnamon.
Prepare Batter: Beat butter and sugar until creamy. Add eggs, vanilla, flour, baking powder, salt, and milk. Mix until smooth.
Layer the Bread: Pour half the batter into the pan, add half the apple mixture, and sprinkle some cinnamon sugar. Repeat layers and swirl lightly with a knife.
Bake: Bake for 50-55 minutes or until a toothpick inserted in the center comes out clean.
Cool: Let the bread cool in the pan for 10 minutes, then transfer to a wire rack.
Make the Glaze: Mix powdered sugar with 1-3 tablespoons milk until smooth.
Drizzle & Serve: Pour glaze over cooled bread, slice, and enjoy!