Heat 2 tablespoons extra-virgin olive oil in heavy large skillet over medium heat. Add sausages. Cover skillet and cook until sausages are brown and cooked through, about 8 minutes per side. Transfer sausages to plate; tent with foil to keep warm. Add garlic to drippings in same skillet and stir 30 seconds. Add broccoli rabe and 1/2 cup broth. Cover skillet and cook until broccoli rabe is crisp-tender, about 8 minutes. Meanwhile, heat 2 tablespoons oil in heavy large saucepan over medium heat. Add polenta; mash with potato masher until smooth. Mix in remaining 1/2 cup broth and cheese. Simmer until polenta is warmed through, about 5 minutes. Season polenta with salt and pepper. Spoon polenta onto 2 plates. Top with sausages and broccoli rabe.