Bring a large pot of salted water to a boil, then cook the pasta until al dente according to package instructions. Drain and rinse with cold water to chill, then set aside in a large bowl.
Meanwhile, heat olive oil in a skillet over medium heat. Add the minced garlic and sauté until fragrant, about 30 seconds to 1 minute — you'll smell that inviting aroma fill the air.
Add the shrimp to the skillet, season with salt and pepper, and cook until they turn pink and opaque, about 3-4 minutes. Turn the shrimp midway to ensure even cooking—notice the color change and firm texture.
Transfer the cooked shrimp to a plate to cool slightly. Once cooled, chop the shrimp into bite-sized pieces if they are large for easier eating in the salad.
Add the cooked, chilled pasta, pesto sauce, and chopped basil into the large mixing bowl. Toss everything together gently with a spoon or tongs, so the pesto evenly coats the pasta and shrimp.
Incorporate the cooked shrimp into the pasta mixture, folding it gently to distribute the seafood evenly throughout the salad.
Taste and adjust the seasoning with additional salt, pepper, or pesto if desired. Chill the salad for at least 30 minutes to let flavors meld and the salad cool thoroughly.
Once chilled, give the salad a gentle toss, garnish with extra basil leaves if you like, and serve in individual bowls or a large shared dish.
