Preheat oven to 350°F (175°C). Grease and line loaf pan.
Brown butter over medium heat until golden and nutty. Cool slightly.
Whisk flour, baking soda, baking powder, salt, and cinnamon.
Mix bananas, brown sugar, yogurt, eggs, and vanilla into brown butter.
Add dry ingredients and mix until just combined.
Fold in chocolate chips.
Pour batter into loaf pan.
Run knife down center and add butter strips if desired.
Top with extra chocolate chips.
Bake 60–65 minutes until golden and fully baked.
Cool before slicing.
Serve warm with butter and flaky sea salt.