1 1/2 pints cherry tomatoes, halved
1 1/4 cups yellow cornmeal
3/4 cup all-purpose flour
1 tablespoon granulated sugar
2 teaspoons baking powder
1/2 teaspoon baking soda
1 teaspoon kosher salt
1/8 teaspoon freshly ground black pepper
2 large eggs
1 cup buttermilk
6 tablespoons unsalted butter, melted and cooled
1 cup fresh corn kernels (from 2 ears)
Arrange a rack in the middle of the oven and heat to 400°F. Cut out a round of parchment and line the bottom of a 10-inch cast iron skillet.
Place the tomatoes in a single layer, cut-side up, on the parchment to cover the entire skillet.
Whisk the cornmeal, flour, sugar, baking powder, baking soda, salt, and pepper together in a large bowl; set aside. Place the eggs, buttermilk, and butter in a medium bowl and whisk until blended. Make a well in the center of the dry ingredients. Pour in the liquid ingredients, then stir with a wooden spoon or rubber spatula just until the ingredients are combined. Fold in the corn.
Pour the batter into the skillet, then smooth it into an even layer over the tomatoes. Bake until the top is golden-brown and the edges have pulled away from the sides of the skillet, 22 to 25 minutes.
Let the cake cool for at least 10 minutes, then run a knife along the edge of the pan. Invert the cake onto a large plate and carefully remove the layer of parchment. Serve hot or at room temperature, sliced into wedges.