Place a rack in upper third of oven; preheat oven to 375°F. Coat a 9-inch square baking pan with cooking spray.
Combine cornmeal, flour, sugar, baking powder, cumin and salt in a medium bowl. Mix milk, butter and eggs in a small bowl; add to cornmeal mixture and stir until almost combined. Add vegetables; stir just until combined. Spoon into pan.
Bake until lightly browned and a cake tester inserted in center comes out clean, about 25 minutes. Cool on a wire rack for 10 minutes before cutting; serve warm.