Add the drained sardines to the skillet, breaking them up gently with a spoon. Cook for 2-3 minutes, allowing them to warm through and infuse with garlic.
Add the cooked and drained pasta to the skillet with the sardines. Stir in the chopped parsley and lemon juice.
Add a splash of reserved pasta water (2-3 tablespoons) to create a light sauce, stirring until everything is well combined and coated. Season with salt and black pepper to taste. Serve immediately.
Notes
Add a pinch of red pepper flakes for heat or some fresh lemon zest at the end for brightness. Any small, short pasta like penne or fusilli works well.