Creamy One Pot Spaghetti with Leeks

Name: Creamy One-Pot Spaghetti with Leeks
Ingredients: 1 tbsp. extra-virgin olive oil; 5 clove garlic; 3 scallions; 2 leeks; 1 medium shallot; 1 anchovy fillet; 1 pinch crushed red pepper; 1 lb. spaghetti; 3.75 c. chicken stock; 0.75 c. heavy cream; 0.5 tsp. kosher salt; 2 tbsp. Chopped chives; 0.25 c. Freshly grated Parmigiano-Reggiano cheese