Preheat oven to 325 degrees F. Grease pan lightly.

Cream butter until it’s light. Beat in the powdered 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 rope detail. Poke all of the surface with a fork, and 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.