In medium saucepan, bring 21/2 cups water and 1/2 tsp. salt to boil. Whisk in polenta. Lower heat to medium-low and cook, stirring frequently, until thick, about 5 minutes. Stir in cheese and 1 tbsp. butter; season. In large nonstick skillet, melt remaining 2 tbsp. butter over medium heat. Add scallions; cook 30 seconds. Crack eggs into skillet, season with salt and pepper and cook to desired doneness. Spoon polenta into bowls. Top with eggs and pancetta. Serve with toast.