In a sizable mixing bowl, combine the large shrimp with olive oil, Cajun seasoning, garlic powder, smoked paprika, salt, and black pepper. Toss to coat evenly and let marinate for 5 minutes.

Place a large skillet over medium-high heat for 2 minutes. Add a splash of olive oil, swirling to coat the pan. Wait until the oil shimmers but does not smoke.

Carefully add the marinated shrimp to the skillet in a single layer. Sauté for 2-3 minutes until pink and opaque. Flip and cook for another 2-3 minutes until evenly cooked and slightly charred.

Remove the skillet from heat and squeeze fresh lemon juice over the shrimp, tossing to coat evenly.

Transfer the shrimp to a serving platter, sprinkle with chopped parsley, and serve warm with rice or crusty bread.