Preheat oven to 350F
Spray a brownie bar pan with nonstick cooking spray OR line an 8x8" baking pan with parchment paper and set aside
Brown the butter in a saucepan over medium-high heat for about 5 minutes, then remove from heat and cool for 2-3 minutes
In a large bowl, whisk together mashed bananas, almond butter, maple syrup, vanilla and eggs until well combined
Whisk continuously while streaming in the slightly cooled brown butter until fully incorporated
Add cocoa powder, baking soda, and salt to the wet mixture and mix until just combined
Fold in a little over half of the chocolate chips
Divide batter evenly among brownie bar pan troughs or add all batter to 8x8" pan
Sprinkle remaining chocolate chips on top
Bake at 350F for 15-20 minutes (brownie bar pan) or 20-25 minutes (8x8" pan) until mostly set in center
Sprinkle with flaky sea salt if desired
Cool for 10 minutes before removing or cutting into 16 squares
Serve warm
