In a medium skillet over medium heat, melt 3 tablespoons of unsalted butter. Add 1 1/4 cups of finely chopped pecans, stirring frequently for about 4-5 minutes until golden and fragrant. Remove and let cool.

In a large mixing bowl, whisk together 2 cups of all-purpose flour, 1 teaspoon of cornstarch, 1/2 teaspoon of salt, 1 teaspoon of cinnamon, and 1 teaspoon of baking soda.

In another bowl, mix the cooled browned butter with 1 cup of dark brown sugar and 1/2 cup of granulated sugar until smooth. Add in 1 teaspoon of pure vanilla extract, 1 large egg, and 1 egg yolk, whisking vigorously for about 2 minutes.

Gradually add the dry ingredient mixture into the wet ingredients, stirring gently with a spatula until just combined; the dough should be slightly sticky.

Gently fold in the cooled toasted pecans using a spatula, ensuring they are evenly distributed throughout the dough.

Cover the dough tightly with plastic wrap and refrigerate for 1 to 2 hours, or up to 24 hours.

Preheat your oven to 375°F (190°C) and line baking sheets with parchment paper. Scoop out tablespoon-sized portions of dough, placing them on prepared sheets.

Bake for 9-12 minutes until edges are lightly golden and centers look slightly soft. Cool on baking sheet for 5 minutes before transferring to a wire rack.