01 -
Preheat the oven to 375°F. Grease a 9x13-inch baking dish with cooking spray or butter.
02 -
Cook the sausage in a large skillet over medium heat for 7-9 minutes, breaking it into small crumbles, until browned and no pink remains. Leave about 2 tablespoons of drippings in the skillet.
03 -
If the skillet looks dry, add the butter. Sprinkle the flour over the sausage and stir for 1 minute, until the flour is absorbed and smells lightly toasted.
04 -
Slowly whisk in the milk. Simmer for 3-5 minutes, stirring often, until thick enough to coat a spoon. Stir in the salt, pepper, garlic powder, and sage if using, then taste and adjust seasoning.
05 -
Spread the hot sausage gravy evenly in the prepared baking dish. Sprinkle cheddar over the top, then arrange the biscuit quarters over the gravy with a little space between pieces.
06 -
Bake for 30-35 minutes, until the biscuits are golden brown, the gravy bubbles at the edges, and the center of the casserole reaches 165°F. Tent loosely with foil if the biscuits brown too fast.
07 -
Let the casserole rest for 10 minutes. Sprinkle with chives if using, then serve warm.