Bring a large pot of salted water to a rolling boil, then add the pasta and cook until just al dente, about 8 minutes. Drain and set aside, reserving a splash of pasta water.
While the pasta cooks, peel and devein the shrimp if needed. Pat them dry and lightly season with a pinch of salt and chili flakes for extra spice.
Heat the olive oil in a large skillet over medium heat until shimmering and fragrant. Add the minced garlic and sauté for about 30 seconds, until it becomes fragrant and slightly golden.
Sprinkle the chili flakes into the hot oil and quickly stir for about 10 seconds. Toss in the shrimp and cook for 2-3 minutes, flipping once, until they turn pink, opaque, and slightly firm, filling the air with a briny, spicy aroma.
Add the drained pasta to the skillet with the shrimp. Toss everything together so the pasta is coated with the spicy garlic oil. If the mixture feels dry, add a splash of the reserved pasta water to loosen everything up and help the flavors meld.
Remove the skillet from heat. Squeeze fresh lemon juice over the pasta, if using, and sprinkle chopped parsley for a burst of freshness. Give everything a final toss to combine the flavors.
Serve immediately while hot, with extra parsley or lemon zest if desired. The dish should be fragrant, fiery, and beautifully coated with garlicky, spicy oil, with the shrimp perfectly tender and pasta al dente.
