Toast the pecans. Spread pecans on a baking sheet and toast at 350°F (175°C) for 7–9 minutes, until fragrant. Cool completely, then chop finely. This step boosts flavor and crunch.

Cream the butter and sugar. In a mixing bowl, beat the softened butter and brown sugar together until smooth and slightly fluffy, about 2 minutes. Add the salt and vanilla, and mix to combine.

Add the flour. Sprinkle in the flour and mix on low just until no dry streaks remain. The dough will look a bit crumbly at first, then come together. Avoid overmixing.

Fold in the pecans. Stir in the chopped pecans evenly. The dough should be soft but not sticky.

Shape and chill. Split the dough in half. Shape each half into a 1.5–2 inch diameter log and wrap tightly in plastic, or press into a flat disc for cut-outs. Chill for at least 1 hour, or up to 2 days. Chilling prevents spreading and gives cleaner edges.

Preheat the oven. Heat to 325°F (165°C). Line two baking sheets with parchment paper.

Slice or cut the cookies. For slice-and-bake, cut logs into 1/4-inch-thick rounds with a sharp knife. For cut-outs, roll the disc between two sheets of parchment to about 1/4 inch thick and cut shapes. Arrange on prepared sheets with a little space between.

Optional sugar finish. Lightly sprinkle the tops with granulated sugar for a subtle sparkle and extra crunch.

Bake. Bake 14–18 minutes, rotating the pans halfway through. The edges should look set and only lightly golden. Shortbread should not brown deeply.

Cool. Let cookies rest on the sheet for 5 minutes, then transfer to a wire rack to cool completely. They will crisp as they cool.