For crust: In the work bowl of a food processor, pulse together flour, cornmeal, and salt. Add butter, and pulse until mixture is crumbly. Add egg and buttermilk; pulse until dough forms a ball. Turn out dough onto to a very lightly floured surface, and shape into a disk. Wrap in plastic wrap, and refrigerate for 1 hour or up to overnight.
Preheat oven to 350°.
Let dough stand at room temperature until slightly softened, about 10 minutes. On a lightly floured surface, roll dough to a 14-inch circle. Press into bottom and up sides of an 11-inch removable-bottom tart pan, Trim excess dough to ¾ inch beyond edges of pan. Fold edges under. Pierce dough all over with a fork. Place tart pan on a rimmed baking sheet, and top with a double layer of parchment paper, letting ends extend over edges of pan. Add pie weights.
Bake until dough begins to set, about 20 minutes. Carefully remove paper and weights. Bake 5 minutes more. Let cool on baking sheet on a wire rack for 15 minutes.
Meanwhile, for filling: Place tomato slices on several paper towels; sprinkle with ¼ teaspoon salt. Let stand for 1 hour.
Pat tomatoes dry with paper towels. Spread corn in an even layer in prepared crust. In a large bowl, whisk together cream, eggs, 4 tablespoons cheese, pepper, and remaining 13/4 teaspoons salt. Pour onto corn. Arrange tomato slices in a circle on cream mixture; sprinkle with remaining 1-tablespoon cheese.
Bake until center is set, about 35 minutes. Let cool in pan on a wire rack for 1 hour before serving. Garnish with chives and basil, if desired.
Recipe by The Ribbon in My Journal - Phyllis Hoffman DePiano at https://www.theribboninmyjournal.com/our-fathers-day-picnic/