In the work bowl of a food processor, pulse flour, cornmeal, salt, and pepper until combined. Add cold butter; pulse until mixture is crumbly. With processor running, add cold buttermilk in a slow, steady stream just until dough comes together.
Turn out dough onto a lightly floured surface. Shape dough into a disk, and wrap in plastic wrap. Refrigerate for at least 1 hour or up to 3 days. Let dough stand at room temperature for 15 minutes before rolling out.
Recipe by Paula Deen Magazine at https://pauladeenmagazine.com/summer-squash-tomato-pie/