Preheat & Prepare the Crust: Preheat your oven to 375°F. Unroll the crescent rolls and lay them out in the bottom of a 9×13 glass baking dish, pressing the seams together to form a crust.
Cook the Sausage & Onion: In a skillet over medium heat, cook the breakfast sausage and chopped onion until the sausage is browned and cooked through. Drain any excess grease and spread the mixture evenly over the crescent roll crust.
Layer the Ingredients: Evenly distribute the thawed hash browns over the sausage mixture, then sprinkle with shredded cheese.
Whisk & Pour the Egg Mixture: In a bowl, whisk together eggs, milk, salt, pepper, and optional seasoning. Pour the mixture evenly over the layers in the baking dish.
Bake to Perfection: Bake for 30-45 minutes, or until a knife inserted in the center comes out clean. Let it cool for a few minutes before slicing and serving.