Begin by creaming the softened unsalted butter and both sugars in a mixing bowl. Beat them until the mixture is light and fluffy, about 2-3 minutes.

Gently add in the large egg, egg yolk, and vanilla extract. Mix until all the ingredients are well incorporated and the batter is smooth and creamy.

In a separate bowl, whisk together the all-purpose flour, baking soda, and salt. Gradually mix this dry blend into the wet ingredients until just combined.

Carefully fold in the toasted, chopped pecans, ensuring they are evenly distributed throughout the dough.

Chill the dough in the refrigerator for about 30 minutes. Once chilled, scoop the dough onto a baking sheet lined with parchment paper, spacing them about 2 inches apart.

Preheat your oven to 350°F (175°C) and bake the cookies for 10-12 minutes, or until the edges are lightly golden yet the centers remain soft.