Most of the recipes we found get that ephemeral apple flavor by boiling down cider until it's a concentrated syrup. Not only does this intensify the flavor, but it allows other liquids to come into the mix - like buttermilk, which helps get that tender crumb! Some recipes also add a little apple butter to the batter for some extra apple-y flavor and darker color.
Topping is a matter of personal preference, of course. We like them rolled in cinnamon and sugar like the doughnuts in the picture above. If you can find them super, hot-out-of-the-oil fresh, then try them plain. That's where the apple flavor really shines, we think.
• Apple Cider Donuts from the Washington Post
• Cider Donut Bread Pudding from Edible Boston - if you happen to find yourself with some leftover donuts! (Scroll to the bottom of the page)
Are you a fan of cider doughnuts?