Preheat oven to 450°F. Unfold pie pastry and gently ease into pie plate. Flute pastry around edge of pie plate. In a large bowl, beat butter, sugar and eggs until smooth. Add cornmeal, lemon peel, lemon juice and vanilla. Beat until thoroughly blended. Pour into pie shell and bake for 10 minutes. Reduce heat to 350°F and continue to bake until a knife inserted in the center comes out clean, or about 30-40 minutes. Cool on wire rack at room temperature for no more than two hours. Serve at room temperature or chilled. Refrigerate leftovers in covered containers.