1. Melt the butter in a medium-sized saucepan or skillet (preferably light-colored so you can better see the color changes) over medium heat. Once the butter has melted, stir it nonstop as you cook it until it begins to brown and light brown specks start forming at the bottom of the pan. This should happen in 5-8 minutes. Remove the butter from heat and pour it into a heat-safe bowl, allowing it to cool slightly for a few minutes.

2. To the melted butter, stir in the brown sugar with a wooden spoon or a spatula. Stir in the egg and vanilla, followed by the mashed banana. Add the flour and salt, and stir until just combined. Stir in the chocolate chips.

3. Pour the batter into the prepared pan. Use a spatula or offset spatula to spread the batter evenly. Top with extra chocolate chips, if desired.

4. Remove from the oven and place the pan on a wire rack to cool. Allow to cool slightly before slicing.