Preheat oven to 350°. Line an 8-inch square baking pan with foil, leaving an overhang on 2 sides.
Using an electric mixer at medium speed, beat butter and brown sugar until creamy. Add vanilla and combine. Reduce mixer speed to low and gradually add flour, beating until well-mixed. Stir in 1/4 cup pecans. Mixture will be crumbly.
Press dough into bottom of prepared pan. Sprinkle top with 1 tablespoon pecans and coarse sugar.
Bake until edges are lightly browned, about 25 minutes. Cool in pan for 10 minutes. Using foil, lift shortbread out of pan. Cut into bars.