In a separate mixing bowl, combine apple cider, egg, sugar, milk, and vanilla. Mix until fully blended.
1 cup apple cider, 1 large egg, ⅔ cup granulated sugar, ½ cup whole milk, 1 teaspoon vanilla
Fold in dry ingredients and butter and mix using an electric hand or stand mixing until smooth and until the dry ingredients are fully combined.
3 tablespoons butter
Add mixture to a large piping bag. See notes for tips.
Pipe filling inside each cavity, filling it up about ¾ full.
Bake donuts for 11-12 minutes. Be sure to stick a toothpick inside once they are done. If the toothpick comes out dry, they do not need to bake any longer.
Allow donuts to cool inside the pans for 2-3 minutes before flipping the pans over onto a wire rack. Allow the donuts to cool on a wire rack until they are near room temperature.
While the donuts cool, combine together the sugar, brown sugar, and cinnamon sugar for the topping.
2 tablespoons melted butter, ¼ cup brown sugar, 1 teaspoon cinnamon sugar, ¼ cup granulated sugar
You can gently brush the donuts with the melted butter using a silicone brush before sprinkling the topping on. Or you can dunk each together into the topping mixture. The donuts will be semi tacky so the mixture should cling nicely.
Enjoy immediately!
Notes
Storage:
To Store: You can store these donuts in an airtight container for 2 days on the countertop or place them in refrigerator for 4 days.
To Reheat: Reheat in microwave for 10-15 seconds if desired.
Tips:
The easiest way to pour the batter into the piping bag is to place the bag in a tall glass and fold down the edges over the rim.
If you do not own a piping bag, you can use a large ziplock bag (gallon sized).
Piping in the mixture makes this process mess free.
Apple cider baked donuts are best eaten right away to enjoy their fresh flavor and soft texture.