earlier. For make-ahead prep, mix the ingredients, press into the buttered glass dish, cover tightly, and refrigerate up to 8 hours before baking; add a few extra minutes to the bake time if it goes into the oven cold.
Food safety notes: always thaw frozen hash browns in the refrigerator or in the microwave, not on the counter, and be sure they stay out of the temperature danger zone (40–140°F / 4–60°C) for as little time as possible. Use sour cream before its expiration date and keep it refrigerated until you’re ready to mix. If you cool leftovers, refrigerate them within 2 hours of baking, store tightly covered, and reheat in a 350°F (175°C) oven or in a skillet until the center is hot and steaming before serving.
