Heat oven to 350°F. Slice peppers in half from stems to bottoms. Remove seeds and membranes. Place pepper halves, cut-side down, in 13 x 9 x 2-inch baking dish and add 1/2 cup water to the dish. Cover dish with plastic wrap and microwave on HIGH for 4 minutes. Remove dish from microwave, carefully remove plastic and drain off water.
Melt butter in medium-size pot over medium to medium-high heat. Add onion and corn and cook for 4 minutes. Add sausage, breaking apart with a wooden spoon. Cook 5 minutes, or until meat is no longer pink. Add remaining 1 cup water and bring to a simmer. Add stuffing mix and stir once or twice. Remove from heat and cover. Let stand 5 minutes. Uncover; gently stir in parsley.
Flip peppers over. Divide filling among peppers, mounding mixture slightly, about 1 cup for each. Top peppers with grated cheese, about 1-1/2 tablespoons for each stuffed pepper.
Bake peppers at 350°F for 18 to 20 minutes, or until cheese is melted and peppers are tender. Serve warm.