Remove the sausage casings, I find it easiest to just squish the insides right out of the ends. Heat a large wide pan with a tall rim, over a medium burner. Add the olive oil, then brown and crumble the sausage. Salt and pepper to taste, and cook for about 3 minutes.
Add the chopped onion and cook for about 3-4 minutes, until the onions soften and become translucent.
Add the kale, and stir until it is wilted, about 1 minute. It will look like a lot in the pan at first, but it will shrink down.
Add the garlic and cook for another minute, being careful not to burn it.
Add the chicken stock, apple cider vinegar, pepper flakes, ground fennel, nutmeg and fresh chopped sage. Stir and cook uncovered for 2-3 minutes to reduce a bit of the liquid.
Add “bunoodles” to the pan, toss and serve.
Garnish with grated Parmesan cheese if you like.