Bring a large pot of salted water to a boil. Add the spaghetti and cook according to package instructions until al dente. Reserve 1 cup of pasta water, then drain the pasta.

In a skillet, heat olive oil over medium heat. Add minced garlic and sauté for 1 minute until fragrant.

Add the shrimp to the skillet, season with salt, black pepper, and red pepper flakes. Cook for 2-3 minutes on each side until shrimp are pink and opaque.

Add the cooked spaghetti to the skillet with the shrimp. Pour in the lemon juice and zest, and toss everything together. If the pasta seems dry, add reserved pasta water a little at a time until desired consistency is reached.

Stir in the chopped parsley and adjust seasoning if necessary. Serve immediately.