Broccoli, Cheddar, and Sausage Breakfast Casserole

About 3/4 lb pork sausage1/2 small onion, diced10 eggsSplash milk or cream1 cup cottage cheese1 cup shredded sharp cheddar cheeseAbout 3/4 cup finely chopped broccoli (I used broccolini)Kosher salt and black pepper