1. Preheat oven to 500 degrees F.
2. Heat a large skillet over medium high heat.
3. Add remaining 2 tablespoons extra virgin olive oil, corn, garlic and chiles. Saute 3 minutes.
4. Add zucchini and yellow squash and onions, season with salt and pepper, chili powder. Cook 7 to 8 minutes.
5. Add stewed tomatoes and heat through. Transfer to baking dish.
6. Cut 1 tube of polenta in 1/2-inch slices lengthwise.
7. Top vegetables with polenta and cheese.
8. Place in hot oven to melt cheese and warm polenta, 8 to 10 minutes.
9. Garnish with chopped scallions and cilantro or flat-leaf parsley.