Preheat the oven to 350℉. Grease doughnut tins* with non-stick spray.
In a large bowl, whisk together the melted butter, sugar, brown sugar, eggs, and vanilla until well combined. Add the sour cream and apple cider and whisk until incorporated.
In another bowl, whisk together the flour, baking powder, baking soda, and allspice. Pour the dry ingredient mixture into the bowl with the combined wet ingredients and stir just until no streaks or large lumps of flour remain. Do not overmix!
Transfer the batter to a Ziploc bag with the corner snipped off or a piping bag fitted with a wide tip. Pipe the batter into the prepared doughnut tins, filling each doughnut well about ½ full.
Bake in the preheated oven for 8-10 minutes or until a toothpick inserted into the center of the doughnut comes out clean. Let cool in the pans for 5 minutes before transferring to a wire rack to cool for at least 10 more minutes. Bake the remaining donuts.
Place the melted butter in a bowl that is at least wider than a donut. In another bowl that size, stir together the sugar and cinnamon. Dunk each cooled donut into the melted butter and then coat in the cinnamon sugar on both sides. Repeat this process with all of the donuts. Enjoy!
Notes
You may use unsalted butter plus ¼ teaspoon of salt for each ½ cup of butter called for in the recipe.
Mix ¼ cup of white sugar with 1 teaspoon of molasses to make homemade brown sugar for this recipe.
Plain yogurt may be used instead.
If you don't have donut tins you could use muffin tins instead.