Bring a large pot of water to a boil. Add salt, and cook the pasta according to package dictions. You’ll want to cook it until just al dente, and then it will finish cooking in the sauce, so plan to take it out a couple of minutes before it is done to your liking.
Meanwhile, in a large, deep skillet, heat the olive oil over low heat. Add the garlic and cook, stirring frequently, for 8 minutes, until the garlic is soft and a very light golden color; do not allow the garlic to brown. Stir in ¼ teaspoon of the red pepper flakes, and season with salt and pepper.
Raise the heat under the garlic oil to medium-high. Add the white wine and simmer for 3 minutes until slightly reduced. Add the chicken broth or stock and the clam juice to the pan and bring to a simmer. Allow to simmer and reduce a bit, about 5 minutes.
When the pasta is just al dente, drain it and return it to the pot. Pour in the broth-clam juice mixture, add the chopped clams and lemon juice, and toss until the pasta is tender and absorbs a bit of the liquid, the clams are heated through, and everything is well combined, about 2 minutes; tongs are great for this. Turn into a serving bowl, and top with additional red pepper flakes, the chopped parsley, and the lemon zest. Serve hot.
Notes
Cook the pasta just short of tender, as it will finish cooking in the sauce, and absorb more of its flavor.
Pass additional red pepper flakes on the side for people to add as they wish.
Leftover pasta may be stored for 2 to 3 days in a tightly covered container in the fridge.
Reheat over low heat, stirring often, until just warmed through. You may need to add a little bit more white wine or water to loosen up the pasta if it is a bit dry.