Cream the Butter and Sugars: In a large mixing bowl using a stand mixer with paddle attachment or an electric hand mixer with beaters attached, cream 1 cup unsalted butter, ½ cup granulated sugar, and ¼ cup light brown sugar until fluffy and completely blended, about 5 to 7 minutes. The mixture should turn a pale yellow color. This extended creaming process incorporates air into the dough, creating a lighter texture in the finished cookies.
Add Egg and Vanilla: Beat in 1 large egg until blended, about 1 minute, and then add 1 teaspoon pure vanilla extract. Make sure to scrape down the sides of the bowl to ensure everything is evenly incorporated.
Incorporate Pecans: Fold in ¾ cup chopped pecans using a spatula or the lowest setting on your mixer. Distribute the nuts evenly throughout the dough for consistent texture in each cookie.
Mix in Dry Ingredients: Gently mix in 2 cups all-purpose flour and ¼ teaspoon salt until just combined. Be careful not to overmix at this stage to avoid developing the gluten, which would make the cookies tough rather than tender and crumbly.
Shape and Chill: Remove dough from the mixer and roll into a log approximately 2 inches in diameter. Cover the dough with a piece of wax paper and refrigerate for at least 4 hours up to overnight. This chilling time is crucial for developing flavor and ensuring the cookies maintain their shape during baking.
Prepare for Baking: Preheat oven to 350°F/177°C. Line baking sheets with parchment paper or leave them ungreased as specified.
Slice and Arrange: Remove dough from the refrigerator and discard the wax paper. Slice the cookie dough into ½ inch slices using a sharp knife. Place cookies on the prepared cookie sheet, leaving about 2 inches between each cookie.
Bake: Bake in the preheated oven for about 12-15 minutes. The cookies will be golden around the edges when done. They may seem slightly soft in the center but will firm up as they cool.
Cool: Remove from the oven and let cool slightly on the baking sheet for 2-3 minutes. Transfer to a cooling rack to finish cooling completely before storing.