Preheat oven to 400 degrees F. Lightly coat a large sheet pan with nonstick spray. Wash and dry the potatoes and then slice in half (or in quarters if they are larger baby potatoes). Place the cut potatoes on the pan.
In a small bowl, add the melted butter, olive oil, garlic, dried parsley, dried oregano, garlic powder, seasoned salt, paprika, and if desired cayenne pepper. Stir or whisk until completely combined. Remove 2 tablespoons of this mixture and toss the potatoes with it until well coated. Place in the oven and bake for 10 minutes. (15 minutes for larger potatoes)
Meanwhile, marinate the shrimp. Place the shrimp in a bowl and toss with 2 and 1/2 tablespoons of the butter-herb mixture. Stir and set aside.
Slice the sausage and prepare the veggies. Cut the onion into 1-inch pieces and cut the bell peppers into 1 inch pieces. (Use one or 2 peppers depending on preference -- if you really like peppers add 2 :)). Throughly drain the canned corn.
Remove the potatoes from the oven and toss with a spatula. Using the spatula, push the potatoes to one side of the sheet pan. Add the sausage, onion, and pepper(s) to the other side of the sheet pan. Add the remaining herb-butter mixture and toss generously to coat. Toss everything together and return to the oven for 10-15 minutes.
Remove from the oven and toss the veggies. Add the shrimp on top of everything and cook for another 12-14 minutes or until shrimp is cooked through and veggies are crisp tender. Stir in drained canned corn immediately after removing from the oven so it can be warmed through.
If desired, top with fresh parsley and parmesan cheese. Enjoy immediately.