Add sausage to a large skillet or heavy-bottomed pot over medium-high heat. Cook and stir with a spatula, breaking apart the sausage until cooked and starting to crisp, 5 to 7 minutes.

Add butter, onion powder, and garlic powder; stir until butter is melted.

Sprinkle flour over sausage and butter and stir until combined. Reduce heat slightly and cook until thick, 1 to 2 minutes.

Pour in chicken stock, scraping up any browned bits from the bottom of the pan. Simmer until stock is absorbed and mixture is thickened, 1 to 2 minutes. Stir in milk until gravy is hot and bubbly.

Season to taste with salt and lots of freshly cracked pepper. If gravy becomes too thick, thin out with more milk.