Bring water and salt to a boil in a heavy saucepan.

Add polenta in a thin stream, stirring with a wire whisk.

Cook over moderate heat, stirring for 2 minutes.

Reduce heat to low, cover pot, and simmer for 10-15 minutes, giving it a good stir every 5 minutes or so.

Taste polenta for doneness. It should be soft with no hard grit. If necessary, add more water and continue to cook.

When polenta is tender, remove from heat, stir in the cheese, parsley, and butter/olive oil.

Season with salt and pepper to taste.

Place polenta in a shallow bowl or spread on a plate, spoon mushrooms on the center of the polenta, and sprinkle with some chopped parsley and grated Parmesan cheese.