Preheat your oven to 350°F. Line a 12-count muffin pan with liners and lightly spray the liners with non-stick spray.
Sift the almond flour, baking powder, baking soda, ground cinnamon, and salt in a medium bowl.
In a large bowl, whisk the brown sugar, sour cream, and eggs until smooth. Add the sifted dry ingredients and mix until just combined.
Mash the banana in a separate bowl until mostly smooth with just a few lumps. Fold the mashed banana into the muffin batter. Fold in the chocolate chips or cinnamon chips and chopped nuts, if using.
Add a scoop of the muffin batter to each liner. Sprinkle the tops with more chopped nuts, chocolate or cinnamon chips, and sparkling sugar, if desired.
Bake in the preheated oven for 19 minutes. A toothpick inserted into the center should come out clean.