Heat the olive oil in a skillet over medium high heat.
Sear the sausage in the skillet until browned. Remove and set aside.
Add two Tbsp of the butter to the skillet, and reduce the heat to medium.
Stir in the onions and saute until softened.
Add the remaining butter to the skillet along with the cabbage.
Sprinkle on the cajun seasoning.
Pour in the heavy whipping cream, and stir to combine.
Cover and simmer until the cabbage is becoming tender.
Remove the lid, and add in the parmesan cheese. Stir to combine, and simmer until thickened.
Return the sausage to the skillet and serve.
