Remove the sausage from the casings, and crumble into a heated pan. Once cooked, remove the sausage with a slotted spoon and set aside. In the sausage oil, saute the onions and garlic, sprinkled with a little salt, until softened.

Meanwhile, bring a large pot of salted water to a boil. Add the kale and cook for 5 minutes. Remove the kale with a skimmer or slotted spoon and add straight to the pan with the onions and garlic. Add the sausage back into the pan and turn off the heat.

Add the pasta to the same pot of salted boiling water and cook until it is al dente. Turn the heat back on your pan. Scoop out ½ a cup of the pasta cooking water and add to the pan, along with the grated Parmesan cheese. Squeeze the fresh lemon juice on top. Then add your drained pasta. Mix everything together well, and taste for seasoning. Adjust with salt, pepper, and optional crushed red chili flakes if desired.
TIP: If you do not have enough sauce to toss your pasta in, just add a little more water and adjust the seasonings.