Bring a large pot of salted water to a boil. Cook pasta according to package instructions until al dente. Drain and set aside.

In a large skillet over medium heat, heat olive oil and cook onions until they are softened. Add garlic and red pepper flakes and cook until fragrant, stirring constantly.

Add kale and 2 tablespoons water, and saute until it wilts, about 5 minutes.

Add Parmesan cheese and cooked pasta to the skillet and stir to coat well. Season with salt and pepper to taste. Serve warm garnished with additional Parmesan cheese if desired.