Parrano Polenta Pizza with Heirloom Tomatoes and Summer Squash

2 pizzas (serves 6-8)

For the Polenta Crust
3 cups water
1/2 teaspoon garlic powder
1 teaspoon dried oregano
1/2 teaspoon salt
1 cup corn grits/polenta
1 cup grated Parrano cheese
1 1/2 tablespoons olive oil

For the Toppings
1-2 (depending on size) heirloom tomatoes, cut into 1/4-inch thick slices
1 small zucchini or yellow squash, sliced into thin rounds
1 cup grated Parrano cheese
6 fresh basil leaves
Black pepper