Reduce apple cider: Add apple cider to a small saucepan. Simmer until the apple cider is reduced by half (you should end up with 1 cup) This should take about 10-15 minutes.Set the mixture aside and allow it to cool.
Cream butter and sugar: Meanwhile, add butter and both sugars to a stand mixer with the paddle attachment. Cream butter and sugar for 4 minutes until fluffy.
Add in the vanilla and whole egg plus egg yolk. Mix to combine.Slowly add in the cooled reduced apple cider and mix to combine.
Combine dry ingredients: In a medium bowl combine the flour, baking powder, baking soda, salt, cinnamon, nutmeg, ground all spice and ground cloves. Set aside.
Add the dry ingredients to the stand mixer. Mix slowly making sure to scrape down the sides. Add in the buttermilk and stir just until combined.
Refrigerate dough: Place dough in the refrigerator for 2 hours to firm up. You can even leave it in overnight.
Roll out dough onto a floured surface (about 1/2 inch thick)Cut out doughnuts: with a lightly floured doughnut cutter or a biscuit cutter (2 1/2 or 3 inch). Cut out the center with a 1 inch cutter for doughnut holes.
Add oil to a large pot with high sides. I do about 6 cups of oil for this recipe. Heat oil to 350 degrees.
Deep fry donuts: Drop your donuts in 2 or 3 at a time. Do not overcrowd the oil with too many donuts. It will lower the heat of the oil substantially.
The donuts take about a minute to cook on each side. If they are browning too easily and not cooking through the center your heat is too high and needs to be turned down.
Make cinnamon sugar coating: Combine the 1/2 tablespoon cinnamon, 5 tablespoons sugar, all spice and ground cloves in a small bowl to coat your doughnuts. Set aside.
Place the doughnuts on a paper towel to drain any excess oil.Immediately dip them in the cinnamon sugar mixture while they are still warm.Serve immediately and enjoy!