Heat a cast iron skillet over medium heat. Add the sausage and cook, stirring and breaking it apart, until it is cooked through, about 5 to 6 minutes.
Transfer the cooked sausage to a bowl using a slotted spoon. Tilt the skillet to collect the grease. Measure and add melted butter to equal 3 tablespoons if you do not have enough grease
Add the onion and cook until softened, stirring frequently to keep from burning.
Return the sausage to the skillet and sprinkle with flour. Stir to combine. Reduce heat to low and allow to simmer for 1 to 2 minutes to brown and cook out the flour taste. Whisk in the warmed chicken stock gradually.
Raise heat to medium low and allow to simmer, stirring frequently, until gravy starts to thicken, about 10 minutes.
Stir in the cream. Allow gravy to simmer, stirring frequently until thick and creamy, about 15 minutes. Season with sea salt and black pepper and stir to thoroughly combine.
Serve immediately, or cover skillet to keep warm until ready to serve.
Farm-raised and organic brands of pork sausage tend to be leaner and have less grease. Each brand is different so just eyeball it and add butter to make up the difference if needed.
Every brand of sausage is different and some are saltier than others. Taste the gravy before adding salt.
You can substitute non-dairy milk, I would suggest unsweetened Cashewmilk, but it will be thinner and not as creamy.
You can substitute coconut milk, shake the can well before opening, but it will add a coconut flavor to your gravy.