Preheat oven to 350°F and grease a 9x13 inch baking dish.
In a large skillet over medium-high heat, brown sausage until no pink remains, breaking it up while cooking. Drain fat.
In prepared dish, layer: thawed hash browns, cooked sausage, diced onions, bell peppers, and 1½ cups cheese. Mix gently and spread evenly.
Whisk together eggs, evaporated milk, salt, pepper, and Italian seasoning in a large bowl.
Pour egg mixture over hash brown mixture and top with remaining ½ cup cheese.
For immediate cooking: Bake uncovered 55-65 minutes until center is set. For make-ahead: Cover with foil, refrigerate overnight, let stand 15 minutes before baking.
Let rest 5-10 minutes before serving.