1.Fill a large pot halfway with water. Bring to a boil on high heat and add salt. Add potatoes and cook until just tender and parboiled, about 10-13 minutes. Stir in corn during the last 5 minutes of cooking time; drain well.
2.Preheat oven to 400 degrees. Line a baking sheet with foil and coat with nonstick spray.
3.In a small bowl, combine butter, olive oil, garlic and Old Bay seasoning, set aside. Cut potatoes into quarters and place potatoes, corn, shrimp and sausage in a single layer onto the prepared baking sheet. Season all ingredients with a dash of salt, ground black pepper, and garlic powder.
4.Drizzle the butter mixture over all the ingredients and gently toss to combine. Place into oven and bake for 12-15 minutes, or until the shrimp are opaque and corn is tender.
5.Top sheet pan with parsley and serve immediately with lemon wedges on the side.