Coat a large nonstick skillet with cooking spray; place over medium-high heat until hot.
Arrange polenta slices in skillet; cook 4 minutes on each side or until edges are crisp. Remove from skillet, and keep warm.
Coat skillet with cooking spray. Add shrimp, and cook 2 to 3 minutes or until shrimp turn pink. Stir in pasta sauce; cook 2 to 3 minutes or until thoroughly heated.
Place 3 slices of polenta on each of 4 serving plates. Spoon shrimp and sauce evenly over polenta; sprinkle with Parmesan cheese. Serve immediately.