Spray a 13x9-inch baking dish with cooking spray. Cut each biscuit in fourths and layer in the pan. It may help to let the biscuits thaw for 10 minutes before doing this step.
Combine the eggs and milk in a large bowl. Whisk together until combined. Season with salt and pepper, set the bowl aside.
Sprinkle the ham in the casserole dish with the biscuit pieces.
Sprinkle the cheese into the dish with the ham and biscuits.
Sprinkle in the sliced green onions. Gently mix the casserole ingredients for even distribution.
Pour the egg mixture evenly over the casserole.
Either cover the casserole and refrigerate overnight, or bake right away. (If you are using dinner rolls, you will want to refrigerate overnight)
Bake at 350 degrees Fahrenheit for 50-60 minutes until the center is puffed, top is browning, and the egg is cooked all the way.
Pour the egg mixture evenly over the casserole. Either cover the casserole and refrigerate overnight, or bake right away.