Place the pie dish on the center rack of the preheated oven and bake for 35–45 minutes, or until the top is deeply golden and crisp, the edges are browned, and you can see a bit of bubbling around the sides through the glass. Ovens vary, so start checking at about 30 minutes and continue until the color looks rich and toasty.
Remove the hash brown pie from the oven and let it rest on a cooling rack for at least 10 minutes. This short rest allows the layers to set up so you can cut clean wedges that show the interior shreds instead of collapsing into a scoop.
Cut into 6–8 wedges directly in the glass pie dish and serve warm. If you like, loosen the edges gently with a thin spatula before cutting, then lift out the first wedge carefully so you keep that layered look intact.
To keep the recipe true to its 1950s clipped-magazine spirit, the base stays at four ingredients, but you can still play a bit at the edges. For a slightly smokier version, use smoked cheddar instead of sharp cheddar. If you want a bit more richness without changing the ingredient list, swap half of the sour cream for full-fat plain Greek yogurt—it keeps the tang while adding a bit of protein.
You can also divide the mixture between two smaller glass pie dishes for more browned edge pieces; just start checking for doneness about 5–10 minutes 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.
