Bring salted water to a boil and add pasta; cook until al dente (while pasta is cooking, reserve about 1 cup of the starchy pasta water and set aside).
Add the cut up bacon to a large saute pan and cook until crispy; carefully remove with a slotted spoon and place onto a paper towel-lined plate.
Carefully remove all but 2 Tablespoons of the bacon grease. Add sliced leeks to the remaining drippings in the pan and cook until they begin to soften, about 3-5 minutes.
Season the leeks with about 1/2 teaspoon each of salt and pepper (adding more or less to taste).
Pour in the half and half and gently stir; let cook for 2-3 minutes.
Add the pasta to the skillet along with the parmesan cheese, 3/4 of the bacon, and some of the reserved pasta water (add as little or as much of the water as needed until the sauce reaches your desired consistency). Stir gently until combined.
Serve topped with the remaining bacon, a sprinkle of parmesan cheese, and black pepper.