1Grease pie plate, 9x1 1/4 inches. Mix cornmeal and cold water in 1-quart saucepan. Stir in boiling water and salt. Cook over medium-high heat, stirring constantly, until mixture thickens and boils; reduce heat. Cover and simmer 10 minutes, stirring occasionally; remove from heat. Stir in Parmesan cheese until smooth. Spread on bottom and up side of pie plate. Cover and refrigerate at least 4 hours until completely firm.
2Heat oven to 350ºF. Cover cornmeal mixture in pie plate with aluminum foil; bake 30 minutes. Cook beef in 10-inch skillet over medium heat about 5 minutes, stirring frequently, until brown; drain. Stir in spinach, pasta sauce and marjoram.
3Spoon beef mixture into polenta shell. Cover and bake 25 to 30 minutes or until heated through. Sprinkle with mozzarella cheese. Bake uncovered about 5 minutes or until cheese is melted. Let stand 10 minutes before cutting.