Boil the pasta - Bring salted water to a boil in a pot. Be sure that you don’t have too much water, so that your pasta water has a good level of starch after boiling. Add the pasta and cook until just al dente, about 7-9 minutes. Drain the noodles, reserving the starch-rich pasta water for finishing the dish later.
Season the shrimp - While the pasta is cooking, add the thawed shrimp to a bowl with 1 tablespoon of cooking oil. Toss to coat. Then season with salt, black pepper, and crushed red pepper flakes. Set aside.
Heat large skillet or outdoor griddle - When the pasta is done, heat a large skillet or outdoor griddle over low heat. *For griddle cooking, turn one griddle burner on low or medium-low and leave the other off to create different temperature zones.
Gently cook the fresh garlic in butter - Add the butter to the heated cooking surface, and then add the fresh sliced or minced garlic to the butter. Gently cook until the garlic is fragrant and just before it starts to brown.
Add the shrimp - Add the raw shrimp to the butter and garlic mixture. Gently toss until the shrimp start to turn pink. *If you started with frozen thawed shrimp, you can also add the liquid from the thawed shrimp at this time.
Add the pasta noodles to the shrimp and garlic butter - When the shrimp are almost cooked through, add the pasta noodles and toss together. Cook the shrimp pasta another 1-2 minutes to ensure that the shrimp are cooked through and the noodles are done to your liking.
Add lemon zest, lemon juice, and pasta water - Add about 75% of the lemon zest, the lemon juice, and about half of the chopped parsley to the shrimp pasta. Let the pasta absorb the lemon garlic sauce, gently moving it between cooler and warmer zones as needed. If the pasta dries out, spoon in about 2-3 tablespoons of the reserved pasta water – this will help the sauce cling and bring the dish together.
Finish with parmesan and fresh parsley - Turn off the heat and sprinkle fresh parmesan, chopped parsley, and the remaining lemon zest over the pasta. Serve immediately.