This is one of those recipes where the almond flour might just work in our favor, as these keto powdered sugar donuts are quite the delight... at just 1g net carb!
Preheat oven to 350°F/180°C. Line (or grease and flour) a mini donut pan (donut hole pan or muffin tray).
Whisk together in a medium bowl almond flour, coconut flour, baking powder, xanthan gum and salt. Set aside.
Add the eggsand sweetener to a large bowl and beat together with an electric mixer until truly lightly and fluffy (about two minutes). This *really* helps with the rise and final texture, so take your time.
Mix in the vanilla extract and the melted butter until well incorporated.
Add in the dry flour mix in two parts, alternating with the sour cream. Distribute batter evenly into the prepared pan, smoothing out the tops with wet fingertips.
Bake for 10-15 minutes (think shorter bake time for the donut holes and longer for the mini donuts), until golden and a toothpick inserted comes out clean. Check in on it after minute 10 though, as I can imagine these ranging a bit depending on pan used used.
Allow to cool completely before rolling in powdered sweetener. Store in an airtight container for 3 days, but do note that powdered sweetener will cake up without adding something like corn or tapioca starch, so its best to add the powdered sweetener right before serving ;)