Preheat oven to 350°F.
Mix flour, baking soda, baking powder & salt in a bowl. Set aside.
In another bowl, combine mashed bananas, sugars, melted brown butter, greek yogurt, heavy cream, spices & vanilla extract.
Fold dry ingredients into wet ingredients until about half combined. Add nuts or chocolate chunks if desired & continue to gently fold until no streaks of flour remain. Small patches of flour are fine, they will absorb.
Heavily grease pan with butter, oil or Bakers Joy (preferred, see recipe), then add batter to pan.
Let rest for 5 minutes before putting into oven.
Top with additional nuts, chocolate chunks or turbinado sugar if desired.
Bake for 50-55 minutes, or until skewer inserted in middle has lots of moist crumbs but no wet batter. If your stick comes out clean, it is overbaked.
Let rest for 5 minutes in loaf pan, then turn out onto a baking sheet or wire rack.
Store in airtight bag. Freezes wonderfully.