Preheat the oven to 400°F.
To make the batter: Add the flour, cane sugar, baking powder, cornstarch, nutmeg, cinnamon, and sea salt to a large mixing bowl and whisk together to combine.
Add the egg, heavy whipping cream, sparkling apple cider, yogurt, melted butter, and vanilla extract. Whisk until combined into a thick batter. Transfer the batter to a piping bag.
Spray the donut pans with avocado oil cooking spray. Pipe the batter into the pans, or if you don’t want to pipe, you can also just spoon it into the pans too!
Bake for 10 to 14 minutes, or until a toothpick inserted comes out clean. Allow to cool completely in the pans.
To make the topping: In a medium bowl, add the cane sugar and cinnamon and mix together. Add the melted butter into a second bowl.
Dip each donut into the melted butter and then dip it into the cinnamon and sugar mixture to coat it completely.
Store in an airtight container for up to 3 days.