Preheat your oven to 350 degrees F. Prepare a 9" x 5" bread pan by spraying it liberally with non-stick cooking spray. This step is crucial to ensure the loaf comes out easily later on.
In a small bowl, prepare the cinnamon sugar mixture. Combine brown sugar with 1 tsp of ground cinnamon, mixing well until combined. Set this aside; it will be layered within the bread.
Now, prepare the apple mixture. In a bowl, combine the diced apples with 2 tablespoons of granulated sugar and the remaining teaspoon of ground cinnamon. Mix until well combined, then set aside.
In a mixing bowl, combine butter and 2/3 cup of granulated sugar. Beat with an electric mixer until light and fluffy—this should take about 2 to 3 minutes. The mixture should look creamy and pale in color.
Beat in the eggs, one at a time, until the mixture is well blended. Make sure each egg is fully incorporated before adding the next one.
Next, add in the vanilla and mix until well blended. This will add a lovely aroma to your batter.
Now it’s time to add the dry ingredients. Gradually add the flour and baking powder to the mixture and stir by hand until well blended. Be careful not to overmix; you want to combine everything just until it’s mixed and no dry flour remains.
Once combined, add in the milk and mix until absorbed. Again, do not overmix—just a few gentle strokes to incorporate.
Scoop slightly more than half of the batter into your prepared bread pan. Spread it evenly across the bottom. Now sprinkle half of the apple mixture over the batter, followed by half of the cinnamon sugar mixture.
Using a knife, gently swirl the mixtures into the batter. This creates that beautiful marble effect once baked. Repeat the layering process with the remaining batter, apples, and cinnamon sugar.
Place the pan in the preheated oven and bake for 50 to 60 minutes. To check for doneness, insert a toothpick into the center; it should come out clean when ready.
Once baked, allow the bread to cool in the pan on a cooling rack for 10 to 15 minutes. This cooling period is essential for the bread to set properly.
Gently run a knife around the edges of the pan to help loosen the bread. Invert the pan to remove the loaf and then allow it to cool completely on the rack.
For the glaze, combine the powdered sugar and 1 tablespoon of milk in a bowl. Stir until smooth and drizzle over the cooled bread once it’s removed from the pan for a sweet finishing touch.
