Cut the (raw) biscuits into fourths and spread on the bottom of a 9x13 casserole pan.
Cook the sausage crumbles and then spread over the top of the biscuit pieces.
Sprinkle on the shredded cheddar cheese.
In a small bowl, whisk together the eggs and milk. Pour over the cheese layer as evenly across the casserole as you can.
Pour the gravy over the top.
Bake at 350°F for 30-35 minutes until bubbly and any visible biscuit pieces look golden brown.
Sprinkle the green onions over the top before serving, if using.
Notes
You can make this casserole the night before by making the recipe up to the point where you pour on the gravy. Cover the casserole and refrigerate overnight. In the morning, pour the gravy over the top and then bake as directed. I use veggie sausage crumbles, but if you are using meat such as pork or turkey, make sure the sausage is cooked through before adding to the casserole. This could change the amount of time it takes to prep this dish.