Heat the oven to 350°F/175°C. Spread pecans on a baking sheet and toast until fragrant and slightly darkened, 6–8 minutes; cool completely, then chop and set aside.
Line 2 baking sheets with parchment paper.
In a medium bowl, whisk together the all-purpose flour, baking soda, and fine salt.
In a large bowl, beat the unsalted butter, granulated sugar, and light brown sugar with a mixer on medium speed until light and fluffy, 2–3 minutes.
Beat in the eggs one at a time, then mix in the vanilla extract until smooth.
Add the dry ingredients and mix on low just until combined; do not overmix.
Fold in the chopped nuts.
Scoop dough into 1.5-tablespoon mounds (about 1.25-inch balls) and arrange 2 inches apart on the prepared sheets.
Bake, one sheet at a time, until edges are set and lightly golden and centers look slightly underdone, 10–12 minutes.
Cool on the sheet for 5 minutes, then transfer cookies to a rack to cool completely.