Begin with the sausages. In a large skillet, heat the oil and butter over medium-high heat.
Sear the sausages until well browned on each side, about 2-3 minutes per side. Remove to a plate and set aside.
In the hot fat, add the onions and sauté for 15-20 minutes, lowering the heat, if necessary, to caramelize. Stir frequently to prevent burning.
Once the onions are deep in color, add the garlic and 1 cup of the stock. Bring to a simmer, add the sausages back in, and place a lid on the skillet. Allow the sausages to cook through.
Once cooked, stir the rest of the stock in with the cornstarch in a small bowl to create a slurry. Whisk until no lumps remain. Add the slurry to the pan and simmer, allowing the gravy to thicken. Place over low heat.
Meanwhile, boil your potatoes until tender. Drain and add the butter, cream, cream cheese, Cajun seasoning, salt, and pepper. Mash using a potato masher until you have your desired consistency.
To serve, spoon a mound of mashed potatoes on a plate. Place a sausage link on top, followed by the onion gravy. To garnish, slice some green onions over the top.
Enjoy!