Heat the oven to 375 F and stir the corn and peppers together in an oval or a 9" square casserole dish.
In a separate bowl, mix the dressing, sour cream, molasses, flour, salt, and pepper together well. Spoon this over the corn mixture, stir it in a bit, and dot the surface with butter.
Cover with foil and bake for 35 minutes, then remove the foil and arrange the tomato slices on top. Sprinkle the Parmesan cheese over the tomatoes and bake uncovered for another 10 minutes.