Set a large pot of water over high heat. Add the salt. Bring to a boil.
While the water is coming to a boil, slice the garlic and put a small sauté over low heat. Add the olive oil, the garlic, and a nice pinch of salt. Let the oil and garlic slowly heat up. You don't want the garlic to brown. You are just warming the oil and letting garlic infuse it.
While the oil and garlic are doing their thing, zest the lemon and wash and dry the arugula.
Once the water comes to a boil, add the pasta and cook until al dente. Drain and reserve some pasta water if you don't have any ricotta whey.
Once the pasta is boiling, turn the heat under the saute pan to as low as it goes and add the ricotta, lemon zest, and a pinch of red pepper flakes. You just want it all to warm it up while the pasta is cooking.
Once you drain the pasta, add it to the saute pan and toss well. Add 1/4 cup of whey or cooking water and the arugula and toss again to coat and wilt the arugula. If you feel it is too dry, add more whey or cooking water. Taste for salt and add the juice from 1/2 a lemon and toss once more.
Serve, topping each bowl with a few sprinkles of coarse salt or fleur de sel and a few drops of lemon juice.