Chicken Sausage Skewers with Cheesy Polenta

Place sausages in a medium nonstick skillet; add about 1/2 inch of water. Cover and cook over medium heat until sausage firms up, 2 to 3 minutes. Remove from skillet; cut into big chunks. Thread sausage, zucchini, and onion pieces alternately onto four (12-inch) skewers. Brush skewers with olive oil. Grill skewers on a nonstick grill pan over medium-high heat, frequently turning and brushing with olive oil, for 10 minutes or until sausage is cooked through. Meanwhile, in a large saucepan, heat 3 cups of water to boiling. Gradually whisk in polenta, 1 teaspoon kosher salt, and 1/4 teaspoon freshly ground pepper. Cook, whisking frequently, for 2 to 3 minutes or until thick and smooth. Remove from heat. Stir in cheeses and 2 tablespoons butter. Spoon onto plates; top with skewers.