Preheat oven to 400°.
Place an 8-inch cast-iron skillet or ovenproof heavy skillet coated with cooking spray over medium heat until hot. Add corn and cumin; sauté 3 minutes or until lightly browned. Place corn mixture in a large bowl; set aside. Coat skillet with 2 teaspoons oil. Place in a 400° oven for 10 minutes or until hot.
Add cornmeal and next 4 ingredients (cornmeal through salt) to corn mixture. Combine 4 teaspoons oil, buttermilk, and egg in a bowl; add to cornmeal mixture, stirring just until moist. Spoon into preheated skillet. Bake at 400° for 40 minutes or until a toothpick inserted in center comes out clean.