3/4 cup (180g) butter (room temperature)
1/2 teaspoon vanilla extract
1/2 cup (50g) confectioners' sugar
1 1/2 (180g) cups flour

Preheat oven to 325°F (162°C). Grease pan lightly.

Cream butter until light and fluffy. Beat in confectioners' sugar, then the vanilla. Finally, work in the flour. Knead dough on an unfloured board until smooth. Firmly press dough into pan, so that it comes up below the edge/top. Prick all of the surface with a fork.

Bake for 30-35 minutes or until lightly browned. Let cool in pan for about 10 minutes. Loosen the edges with a plastic knife and invert onto a cutting board. Cut into serving pieces while warm.

From the wrapper of a Nordic Ware Shortbread Pan.