Bring water and salt to boil in large saucepan. While whisking water in circular motion, pour in cornmeal in a slow steady stream, keeping the water boiling as you do so. Reduce heat to low and continue to cook, stirring constantly, until mixture is thick, from 5 to 15 minutes depending on kind of cornmeal used. Add cream, Parmesan and herbs. Pour into greased pan. Cool and refrigerate, covered. Preheat oven to 400 degrees F. Cut polenta into slices and brush with oil. Place on cookie sheet and bake for 10 to 15 minutes or until heated through.