Preheat the oven to 350ºF and lightly coat a 9×13-inch baking dish with non-stick cooking spray.
In a 12-inch non-stick skillet, cook the bacon until it reaches a crisp texture; then remove and chop it, retaining a portion of the rendered fat in the skillet.
Add the thawed hash browns to the skillet and sauté until they are lightly browned. Transfer the browned potatoes into the prepared baking dish, then sprinkle evenly with the chopped bacon and shredded cheddar cheese.
In a mixing bowl, combine the eggs, milk, and ranch dressing mix, whisking until fully blended. Pour this egg mixture over the contents in the baking dish.
If preparing ahead, cover the dish and refrigerate at this stage.
Bake the casserole uncovered for 60 to 70 minutes, or until the center is set and the top is golden.