In a large pot over high heat, add olive oil. Once hot, add sausage. Sear for a minute on each side, then crumble and cook until browned. Remove sausage with a slotted spoon, leaving 1 tablespoon of grease in the pot and draining off the excess.

Reduce heat to medium. Add butter, onions, carrots, and garlic. Season to taste (I add ½ teaspoon each of salt & pepper). Sauté until tender, about 7–9 minutes. Sprinkle flour on top and cook for another minute, stirring constantly.

Gradually add 1 cup of broth, whisking constantly to create a slurry. Add the remaining broth slowly, whisking and scraping the bottom of the pot. Add Italian seasoning and red pepper flakes, if using.

Bring broth to a boil, then add pasta. Cook according to package instructions, minus two minutes. Stir occasionally to prevent sticking.

Reduce heat to low. Add cream, kale, and return sausage, stirring well. Add Parmesan gradually, ¼ cup at a time, to avoid clumping. Stir until melted. Season with salt as needed. Add more broth for a thinner consistency, if desired.

Serve hot with hearty buttered bread on the side.