Preheat oven to 325 degrees. Prepare a loaf pan by spraying with cooking spray or lining with parchment paper. Set aside.
In a small saucepan, bring the apple cider to a boil. Reduce heat and simmer for 10 minutes.
Remove 1/4 C of reduced cider and add to a small bowl with 1 T cultured butter. Whisk until the butter is melted. Set aside to use for the topping.
Add 1/2 C butter to the saucepan with the hot cider. Whisk until melted. Add the sour cream and vanilla bean paste. Whisk until combined.
In a large bowl, whisk together the eggs and 3/4 C sugar. Add the butter, cider and sour cream mixture from the saucepan. Whisk until well combined.
Add the flour, cornstarch, baking powder, baking soda, dash of salt, cinnamon and nutmeg. Whisk until combined.
Transfer batter to the loaf pan and bake for 50 - 55 minutes, rotating halfway through, until loaf is set.
Allow the loaf to cool in the pan for 10 minutes then remove from loaf pan and place on a sheet of parchment.
For the topping, mix together the sugar, cinnamon and nutmeg in a small bowl. Brush the top and sides of the loaf with the cider and butter mixture. Sprinkle generously with sugar mixture to coat every surface.
Slice and enjoy!
This is my version of the Apple Cider Doughnut Cake Loaf recipe from Bon Appétit.