Start by pouring apple cider into a small saucepan and heat it over medium heat. Allow the cider to simmer for about 15-20 minutes, stirring occasionally, until it reduces to a concentrated ½ cup. Let it cool before using it in your batter.

In a large mixing bowl, combine the melted butter with granulated sugar and brown sugar. Next, add the eggs, sour cream, vanilla extract, and the cooled apple cider. Whisk until the mixture is smooth and well blended.

In a separate bowl, whisk together the all-purpose flour, baking powder, baking soda, ground cinnamon, ground nutmeg, and salt.

Gently fold the dry ingredients into the wet mixture using a spatula. Stir until just combined; be careful not to overmix.

Preheat your oven to 350°F (175°C) while preparing a greased 9x5-inch loaf pan. Pour your batter into the prepared pan and smooth the top. Bake for 45-50 minutes, or until a toothpick inserted in the center comes out clean.

Once baked, remove the pan from the oven and let it cool for about 10 minutes. Transfer the bread onto a wire rack to cool completely.

While the bread is still warm, brush the top with melted butter. In a small bowl, mix together granulated sugar and ground cinnamon. Sprinkle this mixture generously over the warm bread.