Preheat oven to 350°F and grease a 9x5-inch loaf pan with nonstick baking spray. Set aside.
Grate the apple using the largest holes on a box grater. You should end up with about 1¼ cups of shredded apple.
1 large Granny Smith apple
Line a fine-mesh sieve with paper towels or cheesecloth and set it over a bowl. Place the shredded apples into the sieve and sprinkle them with a small pinch of salt. Allow them to sit for 15 minutes.
Squeeze the apples in the paper towels or cheesecloth until all of the liquid has been removed. Discard the liquid-- you should have around ⅓ cup.
In a large bowl, whisk together the flour, apple pie spice, and baking powder. Set aside.
2 cups all-purpose flour, 2 teaspoons apple pie spice, 1 teaspoon baking powder
In a medium bowl, whisk together the brown sugar, applesauce, milk, egg, and vanilla. Whisk until combined.
¾ cup brown sugar, ½ cup applesauce, ¼ cup whole milk, 1 large egg, 1 teaspoon pure vanilla extract
Add the wet ingredients to the dry ingredients and fold them together gently-- you don’t want to overmix!
Once the wet ingredients have been fully incorporated, add the shredded apple and fold it in gently.
Transfer the batter to the prepared loaf pan.
Set the pan aside while you make the streusel.
In a small bowl, combine the flour, brown sugar, and cinnamon. Add the melted butter and mix until the mixture resembles coarse sand.
½ cup all-purpose flour, ½ cup brown sugar, ½ teaspoon ground cinnamon, 2 tablespoons unsalted butter
Spread the streusel evenly over the top of the apple bread.
Bake in a preheated oven for 50-55 minutes, or until a toothpick inserted into the center comes out clean.
Allow the bread to cool in the pan for 5 minutes. Then, run a knife around the edge and turn it out onto a wire rack to cool.