You will never buy jarred Alfredo sauce again when you see how easy it is to make homemade. Pasta with homemade Alfredo sauce is a simple weeknight meal that feels downright indulgent, especially when bacon is involved. Slowly simmer the cream and be sure not to boil it or it will scorch. Cook the vegetables in the bacon drippings for extra richness. To make sure the chopped leeks are free of sand, soak them in a large bowl of cold water for five minutes and then drain.
Bring a large pot of water and 1 tablespoon of the salt to a boil over high.
While water is coming to a boil, cook bacon in a large deep skillet over medium until crisp, turning occasionally, about 8 minutes. Transfer bacon to a plate lined with paper towels, reserving drippings in skillet. Set bacon aside.
Place skillet over medium-high. Add leeks to hot drippings, and cook until wilted and beginning to brown, about 3 minutes. Add peas and garlic, and cook, stirring often, until garlic just begins to brown. Transfer mixture to a medium bowl with a slotted spoon. Reduce heat to medium; add cream to skillet, and bring to a simmer. Cook, stirring often, until slightly reduced, about 5 minutes. Add pepper, nutmeg, and remaining 1 teaspoon salt; stir to combine.
Add pasta to boiling salted water, and cook according to package directions; drain well, reserving 1 cup cooking water.
Finely chop bacon. Toss fettuccine with leek-and-cream sauce mixture over low until heated through. Add reserved 1 cup cooking water, 2 tablespoons at a time, to reach desired consistency. Divide mixture among 4 bowls; top evenly with bacon and Parmesan.