Preheat oven to 350°F/180°C. Grease and flour (with coconut flour) a donut or muffin pan.
Add almond flour, flaxseed meal, psyllium husk, baking powder, xanthan gum and salt to a medium bowl. Whisk until thoroughly combined, set aside.
Add sweetener, molasses (optional) and eggs to a large bowl and beat with an electric mixer for 3-5 minutes until airy, thicker and lighter in color. With the mixer on, add in the apple extract, apple cider vinegar and butter.
Add in the dry flour mixture in two parts, alternating with the sour cream. Continue to mix for a minute or two until fully incorporated and elastic (the batter will thicken as you mix!).
Transfer the batter into a piping bag or plastic bag (no tip needed). Cut out bottom of piping bag roughly 1 inch wide. Pipe out dough onto donut pan, wet your finger tip and smooth out where the ends meet (for a more even rise).
Bake for 23-27 minutes, until golden and a toothpick inserted comes out clean. Watch out after minute 15, and tent with aluminum foil if they begin to overbrown. The donuts will collapse a tad post bake bit, but don't sweat it.
Allow to rest in pan for 10 minutes before removing. Brush with melted butter and sprinkle with cinnamon 'sugar' coating.
Store them at room temperature in an airtight container for 3 days.
This is the natural apple extract I found to result in incredibly believable results (!!). During my trials, I found the optimal quantity of apple extract to be 2 teaspoons. You probably could get away with 3 if really into apples... but definitely don't go as high as 4 or it'll taste medicinal (trust me!). Also do keep in mind that regular apple cider donuts are more subtle than 'in your face' ;)!