Prepare the pecans: Toast the pecans in a skillet over medium heat for a few minutes, stirring constantly to avoid burning. This step enhances the flavor. Let cool and chop finely.
Prepare the base of the dough: In a large bowl, mix the butter, powdered sugar, brown sugar, and vanilla extract. Beat until creamy and fluffy.
Add the yolk: Add the egg yolk and beat again until well combined.
Incorporate the dry ingredients: Add the flour, baking powder, salt, and chopped pecans. Mix with a spatula or with your hands until well incorporated. If the dough feels dry and doesn’t come together, add water, one tablespoon at a time, until the dough holds together without being overly moist.
Shape and chill: Place the dough on plastic wrap, shape it into a log, and wrap tightly. Freeze for 2 to 3 hours or until firm.
Slice and bake: Preheat the oven to 350°F (175°C). Remove the dough from the freezer, and using a sharp knife, slice into rounds about 1 cm thick. Place cookies on a baking sheet lined with parchment paper.
Bake: Bake for 15 minutes or until the edges are slightly golden. Cool on a wire rack before serving.