Pour 2 cups of apple cider into a saucepan over medium-high heat. Simmer for 15–20 minutes until it reduces to about ½ cup.

In a large bowl, whisk together melted butter, granulated sugar, brown sugar, and eggs until smooth. Add sour cream, vanilla extract, and cooled apple cider.

In another bowl, sift flour, baking powder, baking soda, cinnamon, nutmeg, and salt together.

Fold the dry mixture into the wet mixture until just combined.

Pour batter into a greased 9×5-inch loaf pan. Preheat oven to 350°F and bake for 45–50 minutes.

Let the bread cool in the pan for 10 minutes, then transfer to a wire rack.

Brush the top with melted butter and sprinkle with cinnamon sugar while warm.