Preheat the oven to 375F.
In a baking dish, spread out the crescent roll dough sheet. Bake for 7 minutes in the oven, then remove.
While that's baking, cook and brown the breakfast sausage in a pan. In a large bowl, beat the eggs with the sour cream, then fold in the cooked sausage and the cheese.
Pour the casserole filling on top of the pre-baked crescent roll sheet. Next, place the baking dish back into the oven for 40 minutes or until the center of the casserole is finished cooking.
See tips, if you start to see too much browning on the edges.