Cook pasta until al dente.
Heat 2 tablespoon butter in a large pan until melted. Add sliced leeks and saute over medium-low heat for 7-8 minutes, until the leeks soften.
Remove leeks from the pan and set aside.
Return pan to the heat and add remaining tablespoon of butter.
When butter is melted, add minced garlic and cook until fragrant– 1-2 minutes.
Slowly add heavy cream, then add Parmesan ½ cup at a time, whisking until the cheese melts.
Once all cheese is incorporated, add lemon juice and salt and pepper to taste. Stir sauce for 3 minutes over medium-low heat.
Remove sauce from heat. Add cooked pasta to the cream sauce and toss to coat. Add cooked leeks to the pasta and stir to incorporate. Sprinkle with herbs and serve warm. Perfectly delicious topped with grilled chicken or baked fish.