Cook the pasta: Bring a large pot of generously salted water to a boil. Add the pasta and cook according to package directions until al dente. Before draining, carefully reserve 1 cup of the starchy pasta water. Drain the pasta and set aside.

Season and cook the shrimp: While the pasta is cooking, pat the shrimp dry with a paper towel. Season with 1/2 tsp salt and 1/4 tsp black pepper. Heat the olive oil in a large skillet or pan over medium-high heat. Add the shrimp in a single layer and cook for 1-2 minutes per side, until pink and opaque. Do not overcrowd the pan; cook in batches if necessary.

Sauté aromatics: Add the minced garlic and red pepper flakes (if using) to the skillet with the shrimp. Cook for 30-60 seconds, stirring constantly, until the garlic is fragrant. Immediately remove the shrimp and garlic from the skillet and set aside on a plate.

Build the sauce: To the same skillet, add the halved cherry tomatoes. Cook over medium heat for 3-4 minutes, stirring occasionally, until they begin to soften and release their juices. Use a spoon to gently press on a few tomatoes to help create the sauce.

Combine pasta and pesto: Reduce heat to low. Add the drained pasta to the skillet, along with the pesto and 1/2 cup of the reserved pasta water. Toss continuously until the pasta is evenly coated in a creamy sauce. If the sauce seems too thick, add more reserved pasta water, one tablespoon at a time, until it reaches your desired consistency.

Finish and serve: Return the cooked shrimp to the skillet. Add the 1/2 cup of grated Parmesan cheese and the fresh lemon juice. Toss everything together until the shrimp are heated through and the cheese is melted into the sauce. Season with additional salt and pepper to taste.

Serve immediately, garnished with extra Parmesan cheese and fresh basil leaves if desired.