I've made this recipe with every type of shrimp. Fresh, frozen, and fully cooked. If you're really looking for quick and easy, buy pre-cooked, peeled, and deveined cooked shrimp. Fresh shrimp is usually juicier and taste fresher, mainly because they aren't being cooked twice. Whatever you do, make sure frozen shrimp are completely thawed, and patted dry before marinating in pesto.