Start by finely chopping the white part of the leek. Rinse it if necessary.
In a large pot, bring salted water to a boil for the pasta. Cook the pasta al dente according to the package instructions. Remember to reserve about 1/2 cup of the cooking water before draining.
In a skillet, fry the chopped bacon in a bit of oil over medium-high heat until it becomes crispy. Transfer the cooked bacon to a plate lined with paper towels, leaving the bacon fat in the skillet.
Add the chopped leeks to the skillet with the bacon fat and cook them for approximately 3-4 minutes until they become soft and golden. Be cautious not to let them burn.
Add the garlic to the skillet and cook briefly, being careful not to let it brown.
Pour in the stock and cook for a few minutes until the liquid reduces by half.
Add roughly 1/4 cup of the reserved pasta cooking water to the skillet, along with the parmesan cheese and the cooked bacon. Optionally, you can add cream for an extra creamy texture, but it’s delicious without it.
Turn off the heat and add the drained pasta to the skillet. Toss everything together until the cheese melts, and the sauce thickens slightly, coating the spaghetti.
To serve, garnish with plenty of freshly ground black pepper, more parmesan cheese, and a sprinkle of fresh parsley.