1. Preheat the oven to 325°F.
2. In a large bowl, beat the butter and brown sugar on medium speed until creamy. Beat in the vanilla and salt until well-mixed. Reduce the speed to low and beat in the flour until incorporated.
3. Press the dough into a 9-inch round springform or cake pan in an even layer. Press in the pecans.
4. Bake until golden brown, about 25 minutes. Cut into 16 wedges, then cool completely in the pan on a wire rack.
Tip: The shortbread can keep in an airtight container for up to 1 week.