Brown the Butter: In a saucepan over medium heat, melt the unsalted butter. Continue cooking it, stirring frequently, until it turns a fragrant light brown color (5-7 minutes). Remove from heat and let cool.

Combine Sugars: In a mixing bowl, combine the brown sugar and granulated sugar. Pour in the cooled brown butter and mix until well combined.

Add Egg and Vanilla: Crack the large egg into the mixture and add the teaspoon of vanilla extract. Mix until the egg is incorporated.

Dry Ingredients: In another bowl, whisk together the all-purpose flour, baking soda, and salt. Gradually add these dry ingredients to the wet mixture, stirring until just combined.

Fold in Pecans: Gently fold the chopped pecans into your cookie dough.

Chill: Cover the dough with plastic wrap and refrigerate for about 30 minutes.

Preheat your oven to 350°F (175°C).

Shape and Bake: Using a cookie scoop or spoon, drop rounded tablespoonfuls of dough onto a lined baking sheet. Bake for 10-12 minutes, until the edges are golden brown.

Cool: Remove cookies from the oven and let cool on the baking sheet for about 5 minutes before transferring to a wire rack.