Preheat oven to 425°F. Line a large rimmed baking sheet with parchment paper or foil for easy cleanup.
In a mixing bowl combine the halved potatoes and the corn rounds. Toss with half of the melted butter mixture (butter, garlic, Old Bay, Cajun seasoning) until evenly coated. Spread potatoes and corn in a single layer on the prepared baking sheet.
Bake the potatoes and corn for 18 minutes, stirring halfway through cooking.
While the potatoes and corn are baking, in a separate bowl, combine the andouille sausage and shrimp. Toss with the remaining half of the melted butter mixture.
After 18 minutes, remove the baking sheet from the oven. Arrange the seasoned sausages and shrimp around the potatoes and corn on the sheet pan, ensuring everything is in a single layer.
Return the sheet pan to the oven and continue to bake for 8 to 10 more minutes, or until the shrimp are opaque and cooked through and the corn is tender.
Remove from the oven. Garnish generously with chopped fresh parsley and serve immediately with fresh lemon wedges.
Notes
This recipe is a simplified, oven-baked version of the traditional shrimp boil, perfect for a weeknight dinner. For extra flavor, use smoked andouille sausage.