Heat the oil in a skillet over medium heat. Add the onions and sauté for 5 minutes, or until starting to soften. Add the salt. reduce the heat to medium-low and cook stirring every few minutes, or until the onions are very soft, golden brown, and caramelized.
When the onions caramelizing, add lemon and seasoning and keep cooking.
When cooked add the pasta water and cooking cream along with cooked pasta and lemon, cook on low for 2-3 minutes until combined and flavors are infused. Add parmesan cheese, mix and serve.