In a medium pot, boil sliced potatoes until tender (about 15 minutes). Drain and set aside.
In a large pot, crumble and brown the Italian sausage. Drain as much as the fat as you can. Stir in the red pepper flakes, oregano, chicken broth, milk, and half-and-half. Simmer for 30 minutes.
Add the potatoes, a splash of heavy cream for richness, then stir in the kale. Simmer an additional 10-15 minutes, then serve.