In a large stock pot bring 4 quarts of water to boil, add the salt and stir. Add pasta, stir and cook for 9-10 minutes. Scoop out about cup cooking liquid and reserve. Drain pasta (do not rinse) and set aside.
In same large stock pot over medium high heat add the olive oil. Add the sausage meat, salt and red pepper flakes (optional) and break up any large lumps (keep it slightly chunky) and brown on all sides.
Add the wine to deglaze the pan, scraping up the browned bits on bottom of pan. Allow to cook and reduce by half. Add the pesto and cooking liquid and stir. Continue to cook over medium heat and add the fresh spinach. Stir to coat and simmer on low for 5 minutes.
Add the cooked pasta and stir to combine. Serve immediately with fresh parmesan cheese and parsley and fresh lemon (optional).