Bring a pot of water to a boil. Meanwhile, peel the garlic and slice it thinly. Wash the lemon, grate about a quarter of the zest, and squeeze the juice from half of the lemon — set both aside. Place the lemon zest, garlic, and olive oil in a skillet, but do not turn on the heat yet.

Once the water is boiling, add salt and then the pasta. Set a timer to cook the pasta about 30 seconds less than the time indicated on the package.

About five minutes before the pasta timer is done, turn the skillet to medium-high heat. In a bowl, whisk the egg and stir in two-thirds of the Parmesan.

Once the pasta is done and the garlic has turned a light golden brown, remove the skillet from the heat and add the pasta directly from the pot into the skillet. Deglaze with the lemon juice. Gradually stir in the egg and cheese mixture.

Toss the pasta with tongs until the sauce thickens nicely. Then, add a little pasta water at a time, continuing to stir, until the sauce reaches your desired consistency. If needed, thicken with the remaining Parmesan, and season with salt and pepper to taste.

Serve as desired with a little fresh lemon zest, pepper, and the remaining Parmesan.