Preheat oven to 325° Fahrenheit.
Grease muffin tin or loaf pan with non-stick spray, or line loaf pan with parchment paper.
In large bowl, whisk together almond flour, flaxseed meal, baking powder, salt, xanthan gum, and cinnamon. Set aside.
In another bowl, use hand mixer or stand mixer to beat butter and Brown Swerve together on high speed until smooth and creamy, approximately 2 minutes.
Lower speed to medium. Add eggs one-at-a-time, beating mixture well after each addition.
Add in sour cream, banana extract, and vanilla extract. Continue beating mixture on medium speed until combined.
Lower speed to low. While mixing, slowly beat in dry ingredient mixture until all dry ingredients are incorporated and no flour pockets remain. Be careful not to overmix. If using nuts or chocolate chips, fold them in here.
Spread batter into loaf pan, or portion into muffin tin. Top with additional chopped nuts if desired.
Bake 25 to 30 minutes for muffins, or 55 to 60 minutes for bread loaf. To check doneness, insert toothpick or butter knife into center of bread and remove. If utensil comes out completely clean or with few crumbs, baking is done. Top of bread should be lightly browned. Bread will continue cooking slightly while resting.
Remove bread from oven. Let cool in pan completely, then remove and slice.