1. Preheat oven to 425°F (220°C) with rack positioned in upper third. Line large rimmed baking sheet with parchment paper or foil.

2. If using frozen shrimp, thaw completely by placing in colander under cold running water 10-15 minutes, or thaw overnight in refrigerator.

3. Pat shrimp completely dry with paper towels—this is crucial for caramelized edges. Let sit at room temperature 10-15 minutes.

4. Place dried shrimp in large mixing bowl. Drizzle with olive oil or melted butter.

5. Add Old Bay seasoning, minced garlic, lemon juice, black pepper, and cayenne if using. Toss thoroughly with hands or large spoon until every shrimp is evenly coated with seasoning.

6. Spread seasoned shrimp in single layer on prepared baking sheet. Don’t overlap or pile—they need space for even roasting. Use two pans if necessary.

7. Roast on upper rack for 8-10 minutes total, flipping shrimp halfway through (at 4-5 minute mark) for even cooking.

8. Shrimp are done when pink, opaque, and curled into C-shape. Internal temperature should reach 120°F. Don’t overcook—they go from perfect to rubbery quickly.

9. Let shrimp rest on pan 1-2 minutes. They continue cooking slightly from residual heat.

10. Transfer to serving platter. Garnish with lemon wedges and fresh parsley.

11. Serve immediately while hot with small bowls of melted butter for dipping. Provide bowls for discarded shells.