Heat water to boiling in a large saucepan. Add salt. Reduce heat to bring water to a simmer; slowly pour polenta in a thin stream into the saucepan. Stir constantly with a whisk to prevent clumping. After adding all the polenta, stir with a wooden spoon until the polenta is thick and pulls away from the sides of the pan; this may take 15-20 minutes. For best results, stir constantly until the polenta has reached this consistency. Add basil and garlic powder. Stir well.
Wet a paper towel, and rub the bottom and sides of a 9 x 13-inch casserole dish with water to prevent sticking. Once polenta has cooked, transfer it to the dish. With a rubber spatula, press polenta until it is well packed. Cover with plastic wrap and refrigerate 2 hours or until completely cooled.
Preheat oven to broil setting. Using a paper towel, rub a large 11 x 17-inch baking sheet with olive oil and set aside. Remove casserole dish from refrigerator and cut polenta into 2 ½-inch squares.
Place squares on prepared baking sheet, and place 3-4 inches under broiler. Bake 15 minutes, flip, and bake 15 minutes more. Both sides should be crispy before serving.
Yield: 9 servings (serving size: 2 squares)