K-Dub's Sausage and Egg Casserole

Heat a large skillet over medium-high heat and stir in sausage. Cook and stir until sausage is crumbly, evenly browned, and no longer pink, 5 to 7 minutes. Drain and discard any excess grease. Beat eggs, milk, salt and ground mustard in a large bowl. Stir Cheddar cheese and sausage into the egg mixture. Roll out crescent roll dough and place one sheet on the bottom of a large baking dish. Pour egg mixture into baking dish; place the second sheet of crescent roll dough on top. Cover with plastic wrap and refrigerate for 8 hours or overnight. Allow casserole to come to room temperature for 30 minutes before baking; remove plastic. Preheat oven to 350 degrees F (175 degrees C). Bake in the preheated oven until egg is set and a knife inserted near the center comes out clean, about 40 minutes.