1. Grease a 9×13-inch baking dish with butter or nonstick spray.

2. Cook the bacon in a large skillet until crisp, then transfer to a paper-towel-lined plate and crumble once cooled. Pour off most of the drippings.

3. In the same skillet, cook the breakfast sausage over medium heat, breaking it into small crumbles, until browned and cooked through. Drain any excess grease.

4. Spread the frozen shredded hash browns evenly in the prepared baking dish. Scatter the cooked sausage evenly over the hash browns.

5. In a large bowl, whisk the eggs until smooth. Add the whole milk, sour cream, softened cream cheese, ranch seasoning, garlic powder, onion powder, salt, and black pepper. Whisk until mostly smooth; small bits of cream cheese are fine.

6. Stir 1½ cups of the shredded sharp cheddar cheese into the egg mixture.

7. Pour the egg mixture evenly over the hash browns and sausage, gently nudging with a spatula to help it settle into the pan.

8. Sprinkle the remaining ½ cup cheddar cheese over the top, followed by about two-thirds of the crumbled bacon.

9. If making ahead, cover tightly and refrigerate for up to 12 hours. When ready to bake, let the dish sit at room temperature while the oven preheats.

10. Preheat the oven to 350°F (177°C).

11. Bake the casserole uncovered for 40–50 minutes, or until the edges are puffed and lightly browned and the center is just set and no longer liquid. If the top browns too quickly, tent loosely with foil near the end of baking.

12. Remove from the oven and let rest for 10 minutes to finish setting.

13. Top with the remaining crumbled bacon and the sliced green onions or chives.

14. Slice into squares and serve warm.