On low to medium heat, brown 1 cup unsalted butter. Remove the butter from heat when the butter is amber/golden brown in color. Set aside to cool for 10 minutes.

In a bowl, whisk together 2½ cups all-purpose flour, 1½ tsp baking soda, 1 tsp salt, and 1 tsp cornstarch. Set aside.

In a large bowl, add 1½ cups brown sugar, ¼ cup granulated sugar, and the brown butter. Whisk together until it is smooth and combined.

Whisk in 2 egg yolks, ½ cup mashed banana, and 2 tsp vanilla extract. Continue to whisk until the mixture is smooth and lighter/paler in color.

Fold the dry ingredients in with a rubber spatula. Then, add 1½ cups semisweet chocolate chips and ¼ cup mini chocolate chips. The dough will be a bit sticky - if the dough is too sticky, see my tips for success and FAQs above.

Chill the dough in the refrigerator for 30-45 minutes. Preheat the oven to 350 degrees Fahrenheit.

Scoop out 16 equally sized dough balls. Wet your hands slightly before rolling the dough balls to prevent the dough from sticking to your hands. Optional - roll each dough ball in a mixture of regular and mini chocolate chips.

Line a baking sheet with parchment paper and place the cookie dough balls on the sheet. Place in the oven and bake for 12-14 minutes or until the edges are golden and the tops of the cookies still look slightly wet.

As soon as they come out of the oven, shape the cookies with a spoon, bowl, or circular cookie cutter. Top with extra chocolate chips and flaky sea salt.

Let the cookies rest for about 10-15 minutes before transferring to a wire rack to cool. Once on the wire rack, let the cookies cool and set for an additional 15-20 minutes.

Store in an airtight container for up to 3 days or freeze for up to 3 months.