Place the butter in a medium saucepan over medium heat. Allow it to melt, then continue cooking while stirring frequently. Once the butter becomes foamy, golden brown, and fragrant with small brown specks on the bottom of the pan, remove it from the heat.

Let the browned butter cool to room temperature for about 20 minutes. For faster cooling, place it in the refrigerator briefly, but don't allow it to become solid.

In a large mixing bowl, whisk together the cooled browned butter, brown sugar, and granulated sugar until smooth and glossy.

Add the egg yolk, mashed ripe banana, and vanilla extract. Whisk until evenly combined.

Add the flour, baking soda, kosher salt, and cinnamon. Mix gently just until a soft cookie dough forms. Avoid overmixing.

Fold in the chocolate chips or chunks until evenly distributed throughout the dough.

Cover the bowl and refrigerate the dough for at least 1 hour. For deeper flavor, you can chill it for up to 24 hours.

When ready to bake your Banana Bread Chocolate Chip Cookies, preheat the oven to 350°F (175°C). Line baking sheets with parchment paper.

Scoop approximately 2 tablespoons of dough for each cookie and roll or gently shape into balls. Arrange them on the prepared baking sheets, leaving enough room for spreading.

Bake for 10–12 minutes, until the edges look set but the centers remain soft.

Remove the baking sheet from the oven and carefully tap it against a heat-safe counter once or twice. This encourages attractive ripples and helps create chewy chocolate chip cookies with soft centers.

Sprinkle the warm cookies with flaky sea salt. Leave them on the baking sheet for about 5 minutes before transferring them to a wire rack to finish cooling.