As far as food safety goes, you can freeze a potato casserole and bake it later, as long as you store the dish at zero degrees Fahrenheit or colder. At this temperature, bacterial growth slows so the dish stays safe. But freezing can alter the flavor and texture of potatoes slightly, depending on how you prepare the dish.
Like most vegetables, potatoes benefit from a quick dip in boiling water before you freeze them. Blanching them halts the enzyme action that causes them to eventually decay. If you freeze a potato dish without blanching the potatoes first, the potatoes are likely to darken and become mushy. The blanching process adds only about five minutes to your prep time. Peel and slice or dice the potatoes as you normally would. At the same time, heat some water to boiling on the stovetop. Drop the potatoes in the water and cook them for four to six minutes. Drain the potatoes before proceeding with the recipe.
Pick a Potato
The type of potato you use can also make a difference in how well it freezes. Baking potatoes are generally firmer and freeze better than red potatoes, which may become soft. Mature potatoes harvested at the end of the season are also firmer than new potatoes harvested in early summer. Freezing won't improve the quality of the potatoes, so start with fresh potatoes that are free of rot, soft spots or green spots. Cut out any eyes or bruises.
Keep It Together
You should also consider the other ingredients in the dish. Cream sauces, cream cheese and sour cream sometimes separate and become watery after being frozen. Mixing them with other ingredients, such as canned soup or a white sauce, can help stabilize them. You can also stir the dish upon reheating to restore ingredients that have separated.
Wrap It Tight
Because you'll only be freezing the potato dish for a week, it's unlikely to become freezer burnt, but it's still a good idea to wrap the dish to prevent moisture loss. Store the potato dish in a freezer and oven-proof casserole dish. Cover it tightly with aluminum foil. To bake the casserole, thaw it overnight in the refrigerator and bake it until a thermometer inserted in the middle of the dish registers 165 F. You can also bake the casserole frozen, but add extra time to make sure the dish is completely cooked.