Combine flour, cornmeal, baking powder, and salt in a medium bowl. Beat butter and sugar in a large bowl until light and fluffy, about 3 minutes. Add eggs, one at a time, beating well after each addition. Add lemon zest and vanilla. Gradually add flour mixture and beat until well combined. Divide dough into 3 sections and shape into disks. Wrap in plastic wrap and refrigerate 3 hours or overnight.