1. Preheat oven to 350°. Line a loaf pan with parchment, or grease and flour thoroughly. If making muffins, line a 12-cup standard-size muffin tin with paper liners, or grease and flour the cups.
2. In a medium bowl, stir together flour, baking soda, 1 tsp cinnamon, and salt.
3. In the bowl of a stand mixer, or in a separate bowl if using a hand held mixer, cream butter (or oil) and brown sugar on medium speed until fluffy (if using oil, the mixture won’t get fluffy, but mix for about 2 minutes to thoroughly combine the sugar and fat).
4. Add eggs one at a time, incorporating each thoroughly.
5. Lower mixer speed to med-low and add mashed banana and yogurt and mix just until combined.
6. Carefully stir in flour mixture just until combined (don’t overmix).
7. For bread, add half the batter to prepared pan; even it out, and sprinkle half the cinnamon-sugar topping across the top. For muffins, fill cups halfway and add 1/2 tsp of cinnamon sugar to each.
8. Add remaining batter to the loaf pan/muffin cups and top with the rest of the cinnamon-sugar.
9. Bake for 45-50 minutes for a loaf, or 25-30 mins for muffins, until golden brown on top and a cake tester or knife comes out clean, or with a moist crumb or two.
10. Allow to cool before removing from pan/tins

Keep leftovers in an airtight container for up to 3 days, or wrap tightly and freeze. Banana bread freezes best if cut into individual slices that are wrapped individually.