Pre-heat the oven to 325 degrees. Lightly mist a 9x13 baking dish with cooking spray and set aside.

Bring a large saute pan or skillet over medium-high heat and add the sausage. Cook for a couple minutes, breaking it up with a spoon or spatula for about 2 minutes, until it begins to start browning. Add the onion, mushrooms and garlic and continue to cook for another 4-5 minutes until the meat is cooked through and broken up and the vegetables are softened. Transfer the cooked sausage mixture to a large mixing bowl and add the stuffing mix (unprepared). Stir to combine.

Transfer the stuffing and sausage mixture to the prepared baking dish. Drizzle with the chicken broth and melted butter. Sprinkle the cheese evenly over the top.

Combine the milk, egg substitute and pepper in a bowl and whisk together until combined. Pour over the top of the stuffing casserole. Bake for about 40 minutes or until set and cooked through. Let casserole cool for 5 minutes and cut into 9 pieces.