**Reduce the Cider**: Pour the apple cider into a saucepan over medium-low heat. Simmer until reduced to ½ cup, stirring occasionally. This will take about 20-30 minutes. Cool before using.

**Preheat Oven**: Preheat your oven to 350°F.

**Dry Ingredients**: In a medium bowl, whisk together the flour, baking powder, baking soda, salt, nutmeg, cinnamon, and allspice.

**Cream Butter and Sugars**: In a large bowl, use an electric mixer on high speed to cream the softened butter, granulated sugar, and light brown sugar until fluffy, about 2 minutes.

**Add Eggs and Vanilla**: Mix in the eggs and vanilla on medium-high speed until pale and fluffy, about 1 minute.

**Add Wet Ingredients**: On low speed, mix in the buttermilk, sour cream, and reduced cider until combined.

**Combine Dry and Wet**: Add the dry ingredients to the wet ingredients and mix on low speed until just combined.

**Prepare Pan**: Grease a donut pan with nonstick spray. Transfer the batter to a piping bag and cut a ½-inch opening at the bottom. Pipe the batter into the donut pan, filling each well a little more than ¾ full.

**Bake**: Bake for 12-13 minutes, or until a toothpick comes out clean. Cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.

**Melt Butter**: Add the melted butter to a small bowl.

**Mix Spiced Sugar**: In a separate bowl, mix together the granulated sugar, cinnamon, nutmeg, and allspice.

**Coat Donuts**: Brush each donut with melted butter, then roll in the spiced sugar mixture. Serve immediately!