Bring a large pot of salted water to a boil. Cook the pasta according to package instructions until al dente, about 8-10 minutes. Drain, reserving 1/2 cup pasta water.

In a skillet, heat olive oil over medium heat. Add minced garlic and sauté for 1-2 minutes until fragrant.

Add the sardines, breaking them apart gently. Sauté for another 2-3 minutes until warmed through.

Stir in lemon zest and juice, and red pepper flakes if using. Mix well to combine.

Add the drained pasta to the skillet, tossing to coat with sardine sauce. Add reserved pasta water as needed for creaminess.

Season with salt and black pepper to taste. Serve immediately, garnished with parsley and optional Parmesan.