Preheat the oven to 350°F, then grease and line a 9x5-inch loaf pan with parchment if you have it. Use a light coat so the loaf releases cleanly.

Mix the brown sugar and ground cinnamon together, then toss the chopped apples with 2 tablespoons of the cinnamon sugar. Coat the apple pieces so they bake into sweet pockets.

Beat the softened butter and granulated sugar until fluffy, about 1–2 minutes. You should see the mixture lighten in color and look aerated.

Beat in the eggs one at a time, then mix in the vanilla extract until smooth. Stop when the batter looks uniform with no streaks.

Whisk the all-purpose flour, baking powder, and salt together in a separate bowl. This evenly distributes the leavening so the loaf rises evenly.

Add the flour mixture to the batter alternately with the milk, mixing just until combined. Scrape the sides and fold gently to avoid overmixing.

Spread half the batter into the prepared loaf pan, then top with half the cinnamon-sugar apples and half the remaining cinnamon sugar. Keep the layer fairly even.

Repeat the layers with the remaining batter, apples, and cinnamon sugar. The top should look swirled and slightly mounded.

Swirl gently with a knife to create cinnamon streaks through the loaf. Make a few shallow passes rather than fully cutting down.

Bake at 350°F for 50–55 minutes, until a toothpick inserted in the center comes out clean. The loaf should be set and lightly golden on top.

Cool the loaf for 15 minutes in the pan. Let it firm up so the glaze doesn’t soak in too aggressively.

Whisk the powdered sugar with 2–3 tablespoons of milk until thick and drizzleable. Add milk a little at a time to reach a ribbon-like consistency.

Drizzle the vanilla glaze over the warm loaf and let it set. Aim for even coverage so every slice gets a sweet finish.