Add almond flour, flaxseed meal, whey protein, baking powder, xanthan gum and salt into a bowl. Whisk until completely combined, place aside. Note: don't hesitate to create the flour mix ahead in a huge batch and quantify out 80g (or 1/2 cup + 6 TBSP) per bread.
Add egg and sweetener into a large bowl and beat with a whisk or electric mixer for 1 minute or 2 until airy and lighter in colour. With the mixer , add in the apple cider vinegar and butter.
Add in the dry flour mixture in two parts, alternating with the sour cream. Continue to mix for a moment until fully integrated and elastic, and the batter will thicken as you mix (think nearly a cookie dough texture!) .
Transfer the batter into a microwave-safe dish or mold (use either a large one or split into three ramekins), pressing down and smoothing out the shirt with wet fingertips.
If you divide the dough in 3, then you'll cook the bread to get 90 minutes high, but if you cook it all together, you'll want to perform 150 seconds (2 1/2 minutes). Either way, it'll come out looking pale and spongy (and not too appealing at all tbh! ) ) . But worry not, wait for it to cool until only gently warm (it continues to cook as it warms men!) . Then you're going to want to give it an superb toast to acquire some feel on (non-negotiable guys!) .
Store in an airtight container for 2-3 days or in the freezer for a few months. Serve warm with a pat of butter (non-negotiable in my book!).