Begin by preheating your oven to 325°F (163°C). Next, prepare your 9×5 loaf pan by lightly greasing it and then lining it with parchment paper. This little trick will make it so much easier to lift out the loaf once it’s baked, ensuring every last bite is retrieved!

In a small saucepan, pour in your apple cider and bring it to a gentle boil over medium heat. Once boiling, let it simmer for about 10 minutes or until the cider has reduced to about half a cup. Set it aside to cool slightly—this helps to concentrate the flavor beautifully.

Once your cider is cooling, grab a mixing bowl and combine the sour cream and vanilla extract. Once the cider has cooled a bit, add it to this mixture, stirring until combined. Meanwhile, in the same saucepan, gently melt the butter. Let it cool slightly, then move on to the next step.

In a large mixing bowl or stand mixer, beat the eggs together with the brown sugar until the mixture is smooth and frothy. I love using my stand mixer for this, but a good old whisk will do the job just fine. If you’re whisking by hand, don’t forget to use a bit of elbow grease!

With the mixer running on low speed, drizzle in the melted butter. If you’re whisking by hand, do your best to keep mixing while adding the butter. This way, you’ll ensure it’s nicely incorporated.

In another bowl, combine the flour, cornstarch, baking powder, baking soda, salt, cinnamon, nutmeg, and the rolled oats. Whisk everything together until it’s well blended. It’s crucial to ensure even distribution of all those lovely spices.

Now, you’ll want to mix the dry ingredients into the egg mixture, alternating with the cider and sour cream combination. Start and end with the dry ingredients. Be careful not to overmix; a few lumps are perfectly okay. We’re aiming for a tender crumb, after all!

Pour your luscious batter into the prepared loaf pan, smoothing out the top gently. Slide it into your preheated oven and allow it to bake for about 55 minutes. When a toothpick inserted in the center comes out clean, you’ll know it’s done. Just a hint: if you're using a smaller pan, it might take a bit longer!

Once baked, let the loaf cool in the pan for about 10 minutes. Then, using the parchment paper, lift it out and let it cool on a wire rack for another 5 minutes. Time for the fun part—make your sugar topping! In a small bowl, combine the granulated sugar with the cinnamon. Brush the outside of the warm loaf with melted butter and generously coat it with the cinnamon sugar mixture. Keep turning it to make sure all sides get a good layer of that sweet goodness.

Now, try to resist the urge to slice it up right away! Let it cool completely before cutting into it. This loaf is best enjoyed the same day it's made but can be kept for a few days at room temperature.