adapted from "No-Shell Linguine + Clams Recipe" from The Kitchn
Put a large pot of water to boil for the pasta. When it comes to a boil, add salt (like a tablespoon or two).
Heat 2 tablespoons olive oil in a 12-inch frying pan over medium heat then add the fennel (optional), garlic, and shallot. Cook until translucent, a few minutes. Add the red chile flake and cook another minute.
Increase heat to medium-high and add the white wine and optional Pernod. Cook until liquid is reduced by half. Add the remaining 2 tablespoons of olive oil, the juice from the three cans of clams (reserving the clams to add later), and bring to a simmer. Lower heat to maintain a gentle simmer while you cook the pasta.
Add the pasta to the boiling, salted water, and cook very al dente, about 2 minutes less than the package directions. Save some pasta water before draining the cooked pasta, you might need it to loosen the sauce.
Transfer cooked pasta to the pan of clam broth. Add salt and freshly ground black pepper. Cook over medium-high heat, lifting and stirring the pasta into the sauce using tongs and/or a spoon. If the pan is dry, add pasta water a tablespoon at a time.
Add the reserved clams at the last minute and cook until just warmed through, about 2 minutes. Squeeze half lemon over the pasta and add the butter and parsley. Serve with lemon wedges and optional cheese.