Set oven to 350°F and lightly grease a 9x13 casserole dish with non-stick spray.
Arrange half of the biscuit halves in the dish and bake for about 10 minutes, until lightly golden.
In a large skillet, cook sausage over medium heat until browned and crumbly.
Sprinkle in flour and stir for 2-3 minutes. Slowly whisk in milk, salt, and pepper. Bring to a boil, then reduce heat and simmer until thickened.
Pour the sausage gravy over the baked biscuits. Place the remaining biscuit halves on top.
Return the dish to the oven and bake for 25-30 minutes, until bubbly and golden brown.
Let rest for 5 minutes before serving for best texture.