Heat oven to 350. Grease 1 1/2-quart casserole. Mix cornmeal and water in 2-quart saucepan. Add boiling water and salt. Cook over medium heat, stirring constantly, until mixture thickens and boils. Reduce heat. Stir in butter, Parmesan, and thyme. Cover and simmer 10 minutes, stirring occasionally. Remove from heat. Stir until smooth. Spread half the polenta in the casserole. Top with 1/3 cup Swiss cheese. Repeat layers. Bake 15-20 minutes or until hot and bubbly.