Preheat the oven to 350°F. Grease and line a bread pan with parchment paper.
Mix the dry ingredients. In a medium bowl, whisk together the sugar, flour, baking powder, salt, and cinnamon.
Mix the wet ingredients. In another bowl, whisk together the egg, milk, and melted butter until combined.
Combine and add the apples. Gradually add the dry mixture to the wet ingredients, stirring until just combined. Fold in the grated apples. Don’t overmix, a slightly thick batter is perfect.
Make the crumble. In a small bowl, combine the flour, brown sugar, butter, and cinnamon with a fork until crumbly. It should hold together slightly when pinched but still feel loose and sandy.
Layer and bake. Pour half of the batter into the prepared pan and sprinkle a layer of crumble over the top. Add the remaining batter and finish with the rest of the crumble.
Bake for about 60 minutes, or until a toothpick inserted in the center comes out clean. Every oven is a little different, so start checking around the 50-minute mark.
Cool and enjoy. Let the loaf cool in the pan for 10–15 minutes before removing. Slice warm or at room temperature. Either way, it’s delicious.