Sweet potato casserole is a beloved side dish, especially around the holidays. It’s creamy, sweet and pairs perfectly with roasted turkey or ham. However, this dish also tends to get watery as it sits out on the table or in the fridge. So why does this classic casserole end up with so much liquid? There are a few reasons behind this common issue.
Using Too Much Liquid
One of the main culprits for a watery sweet potato casserole is using too much liquid in the recipe. Most recipes call for adding ingredients like milk, cream or juice to the mashed sweet potatoes. This helps thin out the puree and make it easier to mix with spices, sugar, eggs and so on. But go overboard with the liquids and you’ll end up with a runny mess.
Typically, you’ll want to add just enough liquid to moisten the potato puree and allow the ingredients to come together. About 1/4 to 1/3 cup per pound of sweet potatoes is usually sufficient. If your casserole batter seems very loose before baking, you may want to carefully drain off some of that excess liquid.
Tips for Getting the Liquid Right
- Measure your liquids carefully. Don’t eyeball it.
- Start with less liquid and add more as needed.
- Use thicker liquids like cream instead of all milk.
- If the batter is runny, remove some liquid before baking.
Overmixing the Batter
It’s important to mix up all the sweet potato casserole ingredients until fully combined. However, over-mixing can lead to a runny consistency. This is because extended mixing breaks down the starches in the potatoes, releasing more liquid.
You want to mix just until no flour streaks remain and the ingredients are well blended. But don’t beat the batter for longer than necessary. Gentle folding motions are better than vigorous stirring when combining everything.
Tips to Avoid Overmixing
- Mix wet and dry ingredients separately first.
- Fold the wet and dry together rather than beating.
- Stop mixing as soon as the batter looks evenly blended.
- A few small lumps are ok!
Not Draining the Sweet Potatoes
Sweet potatoes contain a lot of moisture. If you don’t drain them properly before mashing, all that excess liquid can lead to watery casserole. Be sure to drain and pat the cooked sweet potatoes very dry before adding other ingredients.
Spread the potatoes out on a baking sheet lined with a clean towel or several layers of paper towels. Let them sit for 15-20 minutes to drain. Then gently press out as much liquid as possible before mashing.
Tips for Draining Sweet Potatoes
- Allow potatoes to steam dry after boiling or roasting.
- Spread on a towel-lined pan and let sit 15+ minutes.
- Gently press or pat to remove as much liquid as possible.
- Avoid squeezing, which can make them gummy.
Using Too Much Egg
Eggs help bind the casserole ingredients together and add richness. But using too many eggs can thin out the batter. Most recipes call for 2-3 eggs per pound of sweet potatoes. More than that can lead to a runny texture.
The moisture in eggs along with extra protein from the whites is often the culprit. Consider using one less egg if your recipe calls for more than 3 per pound of potatoes.
Egg Tips
- Use 2-3 eggs per pound of sweet potatoes.
- Avoid extra egg whites, which thin the batter.
- If batter seems loose, use 1 less egg next time.
Incorrect Baking Time or Temperature
How you bake the casserole also impacts moisture levels. Underbaking can leave the interior underdone and wet. Overbaking causes the potatoes to break down too much and release liquid.
Follow recipe guidelines for baking time and temperature. Typically sweet potato casserole bakes at 350°F for 45-60 minutes. Check for doneness by inserting a toothpick or knife in the center. It should come out clean when the casserole is fully baked.
Baking Tips
- Bake at 350°F for 45-60 minutes until set in the center.
- Use oven thermometer to ensure accurate temperature.
- Cover with foil if top browns before center is done.
- Allow to rest 10 minutes before serving.
Using the Wrong Sweet Potatoes
Believe it or not, the type of sweet potatoes you use can also affect the casserole’s moisture levels. Some varieties are drier than others when cooked.
Opt for drier, starchy sweet potatoes like Jewel or Garnet. Avoid moist, creamy varieties like Hannah or Japanese sweet potatoes, which have a much higher water content.
| Drier Potato Varieties | Moist Potato Varieties |
|---|---|
| Jewel | Hannah |
| Garnet | Japanese sweet potato |
Choosing the Right Potatoes
- Opt for Jewel, Garnet or other dry, starchy types.
- Avoid creamy, moist varieties like Hannah.
- Ask your grocer for a drier sweet potato.
- Test a few varieties and see what works best.
Adding Too Many Moist Ingredients
In addition to liquids, ingredients like applesauce, sour cream, cream cheese or pineapple contain a lot of moisture. Use too many of these in your sweet potato casserole and you’ll likely end up with watery results.
Stick to small amounts of moist ingredients for the best texture. Limit sour cream to 1/4 cup or less per pound of potatoes. Use unsweetened applesauce instead of jelly or juice to cut sweetness. And consider decreasing or omitting cream cheese, which can really loosen up the casserole.
Tips for Moist Ingredients
- Use small amounts of sour cream, no more than 1/4 cup per pound.
- Try applesauce instead of juice to cut sweetness.
- Consider eliminating or decreasing cream cheese.
- Drain and pat pineapple dry before adding.
Not Letting It Set Before Serving
Sweet potato casserole needs time to firm up after baking. If you slice into it immediately, the insides will still be loose and creamy. This can cause water to run out when you serve each portion.
Allow the casserole to rest at room temperature for at least 10-15 minutes before cutting. During this time, the starches will settle and thicken. The end result will hold its shape better without getting watery.
Letting It Set
- Don’t cut into the casserole right after baking.
- Allow to rest at room temp for 10-15 minutes.
- This allows the starches to settle and firm up.
- Serve once the center has firmed slightly.
Storing Correctly
How you store leftover sweet potato casserole also plays a role. Air exposure causes it to dry out in the fridge. But sealing it up traps moisture and can make it watery.
Your best bet is to store leftovers in a container with a slightly vented lid. This keeps some air circulating while retaining enough moisture. You can also mitigate watering by draining excess liquid before storing.
Storage Tips
- Allow to cool completely before refrigerating.
- Drain off any excess moisture after baking.
- Store in a container with a slightly vented lid.
- Seal and freeze portions if not eating within 3-4 days.
Using Wrong Pan Size
The size of baking dish you use can make a surprising difference too. Too large of a pan means the casserole will bake thinner and drier around the edges. But an undersized pan leads to excess moisture with a crowded, almost steamed effect.
Ideally, your baking dish should be just large enough to fit the batter in 2-3 inch deep even layer. This allows the center to bake and set fully before the edges dry out.
Choosing the Right Pan
- Don’t use a pan much larger than the batter amount.
- Aim for an even 2-3 inch layer of batter.
- Crowded pans can lead to excess moisture.
- Glass pans promote even browning.
Forgetting to Grease the Dish
It may seem minor, but failing to grease your baking dish can also contribute to sticking and moisture issues. The sweet potatoes will bake into the pan, making portions difficult to remove cleanly.
Always lightly grease your dish before adding the batter. Butter, oil and parchment paper are all good options. Nonstick sprays also work well for easy release.
Preparing the Pan
- Grease dish with butter, oil or nonstick spray.
- Line with parchment paper for easy removal.
- Ensure the bottom is coated evenly.
- Avoid excessive greasing which can make the bottom mushy.
Conclusion
Sweet potato casserole is prone to watering for several reasons. But with a few simple tweaks, you can keep your holiday side dish from turning into a soupy mess. Be mindful of overdoing moist ingredients. Drain potatoes well and use a properly sized baking dish. Let the casserole rest after baking before serving. And always store leftovers with a slightly vented lid. Follow these tips, and you’ll have picture-perfect slices of sweet potato casserole every time.