For the topping: 6 tablespoons melted butter, 1/2 cup granulated sugar, 1 tablespoon cinnamon
Instructions
Simmer 1.5 cups of apple cider in a small saucepan over medium heat until it reduces to exactly 1/2 cup. This should take about 10-15 minutes. Set it aside to cool slightly before using.
Preheat your oven to 350°F (175°C). Generously grease two 6-cavity donut pans with non-stick cooking spray or a little bit of melted butter to ensure the donuts release easily.
In a large mixing bowl, whisk together the all-purpose flour, baking powder, baking soda, 1 teaspoon of cinnamon, nutmeg, and salt until well combined and free of lumps.
In a separate medium bowl, whisk the egg, brown sugar, and 1/2 cup of granulated sugar together. Add the melted butter, milk, vanilla extract, and the cooled, reduced apple cider. Whisk until smooth.
Pour the wet ingredients into the dry ingredients. Use a spatula to fold the mixture together gently until just combined. Be careful not to overmix, as this can make the donuts tough.
Spoon the batter into the prepared donut pans, filling each cavity about 3/4 full. For a cleaner look, you can pipe the batter into the pans using a large zip-top bag with the corner snipped off.
Bake for 10 to 12 minutes, or until the donuts are lightly golden brown and spring back when touched. Let them cool in the pan for 5 minutes before transferring them to a wire rack.
While the donuts are still warm, metal the topping butter in one bowl and mix the sugar and cinnamon in another. Dip each side of the donut into the butter, then toss it in the cinnamon sugar mixture until fully coated.