One Pan Creamy Gnocchi with Italian Sausage and Kale

mild italian sausage*

olive oil

finely chopped yellow onion

minced garlic

low-sodium chicken broth

milk

bunch kale, (thicks ribs removed, chopped)

pkg. potato gnocchi

Freshly ground black pepper**

heavy cream

(slightly packed) finely shredded parmesan cheese, (plus more for serving if desired)

Red pepper flakes ((optional))