Can You Freeze Sweet Potato Casserole?

Yes. Sweet potato casserole freezes better than almost any holiday side, as long as you freeze the mashed base and leave the topping off. Wrapped airtight at 0°F, it holds its best quality for about 3 months. Thaw it in the fridge for 24 hours and bake at 350°F until the center reaches 165°F.

The topping is the only part that doesn't survive the freezer.

The base is a dense mash of cooked starch, sugar, butter and usually eggs. There's very little free water in it, so ice crystals don't shred it the way they shred green beans or a custard pie. You may see a little liquid at the edges after thawing. A quick stir puts it back.

A grower's note: at Miniature Harvest we never refrigerate raw sweet potatoes, because temperatures below about 50°F give them a hard core and off flavors. That rule is about the raw root. Once they're cooked and mashed, the starch is already set and the freezer does no harm.

Should you freeze it baked or unbaked?

Either works. An unbaked base, eggs and all, freezes fine and tastes slightly fresher because the eggs set only once. A baked base reheats faster. If you bake first, the USDA says to get cooked food into the fridge within 2 hours, so chill it before it goes into the freezer.

1. Line the dish. Line your baking dish with heavy foil, fill it, and freeze it uncovered until solid, about 4 hours.
2. Pop the block out. Lift the frozen casserole out by the foil so your dish isn't stuck in the freezer for a month.
3. Wrap it tight. Press plastic wrap directly onto the surface, then wrap the whole block in foil or a large freezer bag. Exposed air is what causes freezer burn.
4. Label it. Write the date and whether it's baked or unbaked. You won't remember in November.

One caution: don't move a glass dish straight from the freezer into a hot oven. Glass can crack from the sudden temperature change. Thaw first, or use a metal pan.

What about the marshmallow or pecan topping?

Keep it off. Marshmallows go gummy and weep as they thaw. A pecan streusel absorbs moisture from the base and turns soft instead of crunchy.

Streusel does freeze well by itself, though. Mix it, bag it flat, and sprinkle it on straight from the freezer when you bake. Marshmallows go on fresh, always.

How do you thaw and reheat it?

Unwrap the block, set it back in its dish, cover it, and thaw it in the fridge. A full 9x13 takes about 24 hours. The USDA recommends fridge thawing over the counter, and that applies here.

• Baked base. Cover with foil and bake at 350°F for 30 to 40 minutes.
• Unbaked base. Cover and bake at 350°F for 45 to 60 minutes, until the center is set.
• Topping. Uncover, add the streusel or marshmallows, and bake another 10 to 15 minutes until browned.

Check the middle with a thermometer. You want 165°F, which is the USDA's mark for reheated leftovers. If the edges are bubbling and the center is still cool, it needs more time, not more heat.

You can bake it from frozen in a pinch. Keep it covered at 350°F and expect 75 to 90 minutes, with drier edges.

This advice stops applying to casseroles thinned with a lot of milk or cream. Those behave more like custard and weep noticeably. If your recipe uses more than about a cup of dairy per 3 pounds of sweet potatoes, plan on draining or stirring after thawing.

Related: Why Is My Pumpkin Pie Watery?

If you're making it for Thanksgiving, freeze the base the weekend before and mix the topping the morning of. That's how I do it.