Cornbread Focaccia

2 cups cornmeal
1/2 cup all-purpose flour
1 envelope rapid-rise yeast
2 tablespoons sugar
3/4 teaspoon baking soda
3/4 teaspoon baking powder
1 tablespoon dried rosemary

2 cups buttermilk
2 large eggs, slightly beaten
1/4 cup olive oil
1/4 cup onions, finely chopped
1 cup crumbled feta cheese
1 cup black olives, coarsely chopped
1 cup grape tomatoes, sliced in half

Heat a well-greased 12-inch cast-iron skillet in oven for 5 minutes. Stir together all ingredients. Pour into hot skillet.
Bake at 350° for 30 minutes or until golden brown.