In a medium bowl, combine the flour, baking powder, baking soda, cinnamon, nutmeg, and salt until combined. Set aside.
In a small pot, add the apple cider. Bring it to a gentle boil over medium heat. Cook for 20-30 minutes, or until it is reduced by half. You will need it to reduce to ¾ cups (165 grams)! Set it aside to cool to room temperature before using.
Preheat the oven to 350 F/180 C and line a 8.5x4.5 loaf pan with parchment paper.
In a large bowl, whisk together the oil, brown sugar, and granulated sugar until combined.
Whisk in the eggs, vanilla, and sour cream until combined.
Whisk in half of the dry ingredients until combined.
Whisk in the reduced apple cider until combined.
Whisk in the other half of the dry ingredients until just combined.
Pour the batter into the prepared loaf pan.
Bake for 40-50 minutes, or until a toothpick inserted into the center comes out covered in a few moist crumbs.
Let the pan cool on a wire rack for 20 minutes, then lift it out of the pan. Let it cool completely.
Once cool, lightly brush the top and sides of the loaf with the melted butter. Let it soak into the cake for 30-60 seconds.
Then mix together the cinnamon and sugar. Generously sprinkle the loaf with the sugar until completely coated.
Slice and enjoy!