Preheat oven to 350°F. Grease and flour an 8 x 5 inch loaf pan or line it with parchment paper. Set aside.

In a small bowl, whisk together brown sugar and cinnamon and set aside.

In a large mixing bowl, whisk the eggs and granulated sugar together until well combined.

Stir in the melted butter and vanilla extract until smooth.

Add the all-purpose flour, baking powder, baking soda, and salt. Mix until just combined. The batter will be thick.

Gently fold in the chopped apples.

Pour half of the batter into the prepared loaf pan. Sprinkle about three-quarters of the brown sugar mixture over the batter.

Carefully spread the remaining batter on top of the brown sugar mixture. Sprinkle the remaining cinnamon sugar over the top and gently swirl it into the batter using a knife or spoon.

Bake for 35 to 45 minutes, or until the top is golden and a toothpick inserted comes out clean (or with just a few moist crumbs). If the bread is browning too quickly, tent it with foil for the last 10 to 15 minutes.

Let the bread cool completely before slicing and serving.