This pasta dish is always a best seller in Italian restaurants, but very few people try it at home. The sauce only takes about 10 minutes to put together. By then your pasta will be cooked and ready to enjoy this delicious classic dish.
Bring a large pot of lightly salted water to a boil. Cook the spaghetti in the boiling water, stirring occasionally, until cooked through but firm to the bite, about 12 minutes. Drain.
Combine cream, clams with juice, garlic and anchovies in large saucepan over medium heat; bring to a simmer and remove from heat. Add the red pepper flakes and stir.
Beat the egg yolk in a small bowl. Add a tablespoon of hot cream mixture to the egg and stir. Repeat twice. Pour the egg yolk mixture into the cream mixture and stir.
Add cooked spaghetti to cream mixture; toss to coat the pasta, cover the pot and let stand until the flavors combine and the pasta absorbs some of the sauce, about 5 minutes. Sprinkle Parmesan cheese on top and season with salt. Serve pasta in bowls; Top with croutons and basil.