In 10-inch nonstick skillet, heat 1 teaspoon of the oil over high heat. Cook 6 polenta slices in oil about 5 to 8 minutes, turning once, until golden brown. Repeat with remaining oil and polenta slices. Remove from skillet; cover to keep warm.
In same skillet, cook chicken, onion, bell pepper, garlic, Italian seasoning, sugar and salt over medium-high heat 5 minutes, stirring frequently. Stir in tomatoes and mushrooms. Heat to boiling; reduce heat to medium-low. Simmer uncovered 3 to 5 minutes or until chicken is no longer pink in center.
Serve chicken mixture on polenta slices. Sprinkle with parsley.