Preheat oven to 400°. Place potatoes in a 15x10x1-in. baking pan. Drizzle with oil and sprinkle with Italian seasoning; toss to coat. Bake until tender, 25-30 minutes. Using a potato masher, flatten potatoes to 1/2-in. thickness; remove and keep warm.
Add corn, mussels, clams, shrimp and chorizo to same pan; top with potatoes. Pour wine into pan. Squeeze lemon wedges over top; add to pan.
Combine butter, garlic, seafood seasoning and Cajun seasoning. Pour half the butter mixture over top. Bake until shrimp turn pink and mussels and clams open, 20-25 minutes. Discard any unopened mussels or clams.
Drizzle with remaining butter mixture. Sprinkle with pepper; top with parsley. If desired, serve with bread.