Reduce the Apple Cider: In a small saucepan over medium heat, bring 1.5 cups of apple cider to a gentle simmer. Cook for 15 to 20 minutes until reduced to exactly 1/2 cup of deep amber syrup. Pour into a small glass cup and let cool for 10 minutes.

Preheat & Prep Donut Pans: Preheat oven to 350°F (175°C). Generously grease two 6-cavity non-stick donut pans with baking spray or melted butter.

Whisk Dry Ingredients: In a large bowl, whisk together flour, baking powder, baking soda, ground cinnamon, nutmeg, allspice, and salt until thoroughly combined.

Mix Wet Ingredients: In a medium bowl, whisk together melted butter, egg, brown sugar, granulated sugar, buttermilk, vanilla extract, and the 1/2 cup of reduced cider until smooth and glossy.

Combine into Batter: Pour the wet mixture into the dry ingredients. Fold gently with a spatula just until the flour is incorporated—do not overmix. Transfer batter into a large gallon zip-top or piping bag and snip the corner off.

Pipe & Bake: Pipe batter evenly into the 12 donut cavities, filling each about 3/4 full. Bake at 350°F for 11 to 13 minutes until the tops spring back when gently pressed. Let cool in the pan for 5 minutes, then invert onto a wire rack.

Dip & Coat in Cinnamon Sugar: In a shallow bowl, whisk granulated sugar and ground cinnamon. Melt 6 tablespoons of butter in a second shallow bowl. While donuts are still warm, lightly dip both sides into melted butter, then toss generously in the cinnamon sugar until completely coated. Serve warm!