Preheat the oven to 350°F (175°C) and line a 9x5-inch loaf pan with parchment paper (this is a must to avoid sticking).

Reduce the apple cider: Add the apple cider to a saucepan over medium heat and boil. Reduce to a simmer and cook until reduced by half (around 120 grams), about 15-20 minutes. Remove from the heat and set aside to cool.

In a large mixing bowl, whisk together the melted butter, oil, apple cider, vanilla, sourdough discard, applesauce, eggs, brown sugar, and granulated sugar until well combined.

In a separate bowl, whisk together the flour, cornstarch, baking powder, baking soda, salt, cinnamon, and nutmeg.

Add the dry ingredients to the wet ingredients and gently fold together just until no dry streaks of flour remain. Do not overmix. The batter should be thick but easily pourable/spreadable.

Pour the batter into the prepared loaf pan and smooth the top. Bake for approximately 50–60 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs. If the top begins browning too quickly, loosely tent the loaf with aluminum foil for the remainder of the baking time.

Allow the bread to cool in the pan for about 10–15 minutes before carefully removing it. Let it cool slightly on a wire rack.

Stir together the granulated sugar and cinnamon. While the loaf is still slightly warm, brush the outside generously with melted butter, then sprinkle the loaf with the cinnamon sugar mixture until well coated. Place parchment paper underneath the loaf as it gets a little messy.

Allow the coating to set for a few minutes before slicing. Enjoy warm or at room temperature.

Store the bread tightly wrapped or in an airtight container at room temperature for up to 3 days. For longer storage, refrigerate for up to 1 week or freeze slices for up to 3 months.