Preheat the oven to 350F. Grease and line a standard (9x5") loaf pan with parchment paper. Set aside.
Start by browning the butter. Add the butter to a saucepan over medium-high heat. Allow to melt and slightly brown (~5 minutes). Remove from the heat and allow to let it cool slightly.
In a medium bowl whisk together the flour, baking soda, and baking powder, and salt. Set aside.
Once the brown butter has cooled, add the browned butter, mashed bananas, eggs, brown sugar, sourdough discard, greek yogurt, and vanilla to a large bowl. Whisk together until well combined.
Add the dry ingredient mixture to the wet. Use a wooden spoon or spatula to fold together until well combined but not over-mixed.
Fold in the chocolate chips.
Pour the batter into the prepared loaf pan, and top with more chocolate chips/chunks if desired.
Bake at 350F 55-65 minutes, until golden brown and a toothpick inserted into the middle comes out clean.
Let cool for 5-10 minutes in the pan. Then remove from the pan and transfer to a serving plate or wire cooling rack.
Slice and serve warm with butter and flaky sea salt, if desired.
