Preheat your oven to 350°F. Spray a 9×5-inch loaf pan with nonstick spray to ensure the bread releases easily.
In a small bowl, combine ⅓ cup of brown sugar, 1 teaspoon of cinnamon, and the diced apples. Stir well and set this mixture aside. This will be your apple filling.
In a large bowl, use a hand or stand mixer to beat together ½ cup of granulated sugar and ½ cup of unsalted butter until the mixture is smooth and creamy. This is where the magic begins!
Add 1 large egg and ¼ cup of unsweetened applesauce to the mixture and mix until fully combined. Don’t forget to add in 1½ teaspoons of pure vanilla extract for that extra flavor.
In a separate medium bowl, whisk together 1½ cups of all-purpose flour, 1¾ teaspoons of baking powder, and ¼ teaspoon of kosher salt. Gradually add the dry ingredients into the wet ingredients, mixing as you go.
Slowly pour in ½ cup of milk while continuing to mix. The batter should be smooth and slightly thick.
Now, it’s time to assemble! Pour half of the batter into the prepared loaf pan and spread it evenly.
Sprinkle half of the remaining brown sugar and half of the remaining cinnamon over the top. Layer half of the apple mixture on top.
Pour the remaining batter over the apple layer and then sprinkle the rest of the apple mixture, brown sugar, and cinnamon on top. If you like, you can add a coffee cake crumble topping at this point.
Bake for 45 to 50 minutes, or until a toothpick inserted into the center comes out clean. You’ll know it’s done when the top is golden brown.
Let the bread cool in the pan for 10 minutes before transferring it to a wire rack. This helps it firm up and makes it easier to slice.
If you're using the crumble topping, mix together 4 tablespoons of melted unsalted butter, ½ cup of all-purpose flour, ½ cup of brown sugar, 1 teaspoon of cinnamon, and ½ teaspoon of kosher salt. Sprinkle it over the batter before baking.
For the glaze, mix ½ cup of powdered sugar with 2 tablespoons of milk. Add more milk until you reach your desired consistency. Drizzle over the cooled bread after baking.
