Place the unsalted butter in a medium saucepan over medium heat. Melt the butter, then continue cooking, whisking constantly. The butter will foam up and then begin to develop little brown specks at the bottom. Once it smells nutty and looks golden brown, remove it from the heat immediately. Pour it into a large mixing bowl and let it cool for about 10 minutes.

While the butter cools, place your chopped pecans in a dry skillet over medium heat. Toss them frequently for 3 to 5 minutes until they become fragrant. Remove them from the pan and set them aside to cool. Toasting the pecans is essential for bringing out their natural oils and crunch.

Add the brown sugar and granulated sugar to the cooled brown butter. Whisk until smooth. Add the egg, maple syrup, maple extract, and vanilla extract. Beat the mixture vigorously for about one minute until it becomes pale and well-combined.

In a separate bowl, whisk together the flour, baking soda, and sea salt. Gradually add the dry ingredients to the wet mixture, stirring with a wooden spoon or spatula until just combined. Fold in the toasted pecans until they are evenly distributed throughout the dough.

Cover the bowl and refrigerate the dough for at least 30 minutes. This prevents the cookies from spreading too much in the oven and allows the flavors to deepen. While the dough chills, preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper.

Scoop rounded tablespoons of dough (about 2 tablespoons per cookie) and place them 2 inches apart on the prepared baking sheets. Bake for 9 to 11 minutes, or until the edges are lightly golden but the centers still look slightly soft. Let them cool on the pan for 5 minutes before transferring them to a wire rack.