Best Apple Cider Donut Cake – With Cinnamon-Sugar Topping

Ingredients

• 1½ cups apple cider
• ⅔ cup sugar
• 2 large eggs
• ⅔ cup sour cream
• ½ cup (1 stick) unsalted butter, melted and slightly cooled
• 1¼ teaspoons ground nutmeg
• 1 teaspoon vanilla extract
• ½ teaspoon salt
• 1½ cups all-purpose flour, (spooned into measuring cup and leveled-off)
• 1½ teaspoons baking powder
• ½ teaspoon baking soda
• Reduced cider, (reserved from making the cake)
• 2 tablespoons unsalted butter
• 2 tablespoons sugar
• Big pinch salt
• ¼ teaspoon cinnamon