Cream the softened butter and packed light brown sugar together using an electric mixer on medium speed for 3-4 minutes until pale and fluffy.

Add the egg and pure vanilla extract, mixing on medium speed for 1-2 minutes until smooth.

Sift together the all-purpose flour and baking powder in a separate bowl, then gradually mix into the wet ingredients on low speed until just combined.

Fold in the finely chopped pecans using a spatula until evenly distributed.

Drop dough onto prepared baking sheets, spaced about 2 inches apart, and optionally press additional pecans on top.

Preheat oven to 350°F (175°C) and bake the cookies for 10-12 minutes until the edges are golden brown.

Cool the cookies on baking sheets for about 5 minutes before transferring to a wire rack.