Reduce the Apple Cider: In a small saucepan, bring 1 1/2 cups of unfiltered apple cider to a gentle boil over medium heat. Simmer uncovered for 15 to 20 minutes until reduced to exactly 1/2 cup of intensely concentrated amber liquid. Remove from heat and let cool to lukewarm.

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

Whisk Dry Ingredients: In a large bowl, whisk together the flour, baking powder, baking soda, ground cinnamon, nutmeg, cloves, and sea salt until uniformly aerated.

Combine Wet Ingredients: In a separate medium bowl, whisk together melted butter, brown sugar, and granulated sugar until well combined. Whisk in the eggs one at a time, followed by the vanilla extract, buttermilk, and cooled reduced apple cider until smooth and silky.

Fold the Batter: Pour wet ingredients into the dry ingredients. Using a rubber spatula, fold gently just until no dry flour pockets remain (do not overmix, as this keeps the crumb light and tender).

Pipe into Donut Pans: Transfer batter into a large gallon zip-top bag or piping bag and snip off a 1/2-inch corner. Pipe batter evenly into the prepared donut cavities, filling each cavity about 3/4 full.

Bake to Golden Perfection: Bake at 350°F (175°C) for 11 to 13 minutes, or until the donuts spring back lightly when pressed with your finger and a toothpick inserted into the center comes out clean.

Coat in Cinnamon Sugar: Allow donuts to cool in the pan for 5 minutes, then invert onto a wire cooling rack. In a shallow bowl, whisk granulated sugar and ground cinnamon. Working while donuts are still pleasantly warm, lightly brush all sides with melted butter and generously dredge in the cinnamon sugar mixture until completely coated. Serve warm!