In a medium saucepan, melt the salted butter over medium heat. Continue cooking, stirring frequently, until the butter turns golden brown and develops a nutty aroma. This should take about 5-7 minutes. Remove from heat and let it cool slightly.
In a large mixing bowl, combine the light brown sugar and granulated sugar. Pour in the browned butter, along with the vanilla extract and molasses. Mix until well combined. Add the egg and egg yolk, mixing again until smooth.
In another bowl, whisk together the all-purpose flour and baking soda. Gradually add the dry mixture to the wet ingredients, stirring until just combined. Be careful not to overmix!
Gently fold in the bittersweet chocolate chips and both types of chopped pecans. The mixture will be thick and deliciously chunky.
Cover the bowl with plastic wrap and chill the dough in the refrigerator for at least 30 minutes. This step is crucial for achieving the perfect texture in your cookies!
While the dough is chilling, preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper and set aside.
Using a cookie scoop or tablespoon, drop rounded balls of dough onto the prepared baking sheets, leaving enough space between each cookie to allow for spreading. Sprinkle a pinch of coarse sea salt on top of each cookie before baking.
Bake the cookies in the preheated oven for 10-12 minutes, or until the edges are golden but the centers are still soft. Remove from the oven and let them cool on the baking sheets for a few minutes before transferring to a wire rack to cool completely.