01 -
Grease and line a 9 x 4 inch loaf tin with parchment paper. Preheat oven to 350°F (180°C).
02 -
In a medium bowl, whisk together the flour, baking powder, baking soda, salt, and 1 teaspoon ground cinnamon. Set aside.
03 -
In a large mixing bowl, beat the butter and granulated sugar on high speed until light and fluffy, about 3 minutes.
04 -
Add eggs one at a time to the butter mixture, mixing well after each. Whisk in vanilla extract until combined.
05 -
Fold in half of the dry ingredients until just incorporated. Add all of the buttermilk and mix until combined, about 30 seconds. Gently fold in the remaining flour mixture until no dry streaks remain. Do not overmix.
06 -
In a small bowl, toss diced apples with brown sugar and 1 tablespoon ground cinnamon until evenly coated.
07 -
Pour half of the batter into the prepared loaf tin. Evenly distribute half of the apple mixture over the batter and gently swirl with a knife. Add remaining batter, top with the rest of the apple mixture, and gently swirl again.
08 -
Bake for 55 to 65 minutes. Cover loosely with aluminium foil after 30 minutes to prevent excessive browning. The loaf is done when a toothpick inserted in the center comes out clean.
09 -
Remove from oven and set loaf tin on a rack for 10 minutes. Carefully lift loaf out and cool completely on rack before slicing and serving.