Easy Peasy! Dynamite dish that's both casual and impressive!
Bring a large pot of water to a boil. Add the salt and cook the pasta according to package directions until al dente. Reserve 1 cup of the pasta water when straining.
In the meantime, heat a very large sauté pan and add the olive oil. Cook the shrimp until they turn pink, a couple minutes on each side. Do not crowd the pan, cook in batches if needed. Remove shrimp and set aside.
Add the butter and leeks to the pan and cook until softened. Add the garlic and cook for another minute. Add the cooked pasta to the pan along with the shrimp and peas. Stir in the lemon zest and juice and season with salt and pepper. Stir in the half and half and when fully heated, add the cheese. If dry, add a little reserved pasta water as desired. Mix well.
Top with parsley and additional Parmesan.