Heat the olive oil in a large Dutch oven over medium heat. Add the onion and cook, stirring occasionally, for 2-3 minutes, or until softened. Add the sausage along with the crushed red pepper flakes and cook for 3-4 minutes, stirring often, making sure to break the meat up into crumbles. Add the minced garlic and cook, stirring constantly for 1 minute. Add the roasted red pepper and chicken broth.
Simmer for 10 minutes then add the gnocchi and kale. Simmer for another 10-15 minutes or until the gnocchi is tender and cooked through. Add the milk and fresh basil then stir until well combined. Taste the soup and season with sea salt and freshly cracked pepper, to taste. Serve with Parmesan if desired.