Healthy sweet potato casserole, and where the sugar really is
Sweet potatoes bring about 6 g of sugar a serving on their own. This casserole adds 3 tbsp of brown sugar to the whole dish, for about 289 calories a serving.
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Ingredients
- 1120 g sweet potatoes, peeled and cut into 3 cm (1 inch) chunks
- 28 g unsalted butter, for the mash Out of butter?
- 120 g sour cream Out of sour cream?
- 2 eggs, beaten
- 28 g light brown sugar, packed, for the mash Out of brown sugar?
- 1.04 tsp vanilla extract Out of vanilla extract?
- 1.04 tsp ground cinnamon
- 52 g pecans, chopped, for the topping
- 40 g rolled oats, for the topping
- 14 g light brown sugar, packed, for the topping Out of brown sugar?
- 14 g unsalted butter, melted, for the topping Out of butter?
Method
- Heat the oven to 180C (160C fan, 350F). Put the sweet potato chunks in a large pan, cover them with cold water, add a pinch of salt and bring to the boil. Simmer for 12 to 15 minutes, until a knife slides into the biggest piece with no resistance.
- Drain them well, then tip them back into the hot, empty pan over a low heat for a minute, shaking it, to drive off the water clinging to the outside. A wet mash is the reason most sweet potato casseroles weep in the dish.
- Mash with the butter for the mash, the sour cream, the sugar for the mash, the vanilla, the cinnamon and a pinch of salt. Use a masher or a hand mixer rather than a food processor, which works the starch until the mash turns gluey.
- Leave it for 5 minutes to cool a little, then beat in the eggs. Added to a mash straight off the heat, they scramble in streaks.
- Spread the mash in a baking dish of about 2 litres (2 quarts), such as a 20 cm (8 inch) square.
- Stir the pecans, oats, the sugar for the topping and a pinch of cinnamon together, then add the melted butter and mix until the oats are coated. Scatter it evenly over the top.
- Bake for 30 minutes, until the edges have puffed slightly and the topping is golden. If the nuts are darkening before the middle has set, lay a sheet of foil loosely over the dish for the rest of the time.
- Leave it to stand for 10 minutes before serving. The filling firms up as it settles.
The quickest way to make sweet potato casserole healthier is to cut the added sugar, because the sweet potatoes already bring about 6 g of sugar a serving on their own. This version adds 3 tbsp of brown sugar to the whole dish, and comes to about 289 calories and 12 g of total sugar a serving by our estimate.
Most of those calories are the potato and the pecan topping, which is where the rest of this page goes: what each choice costs, and which “healthy” swaps are not lighter at all.
How can I make sweet potato casserole healthier?
By choosing the sugar and the topping on purpose, since those are the two decisions that move the numbers. Per serving, for a dish that serves eight, by USDA values.
| Choice | kcal | Sugar |
|---|---|---|
| Brown sugar in the filling, 1 cup | 105 | 27 g |
| Brown sugar in the filling, 1/2 cup | 52 | 13 g |
| Brown sugar in the filling, 2 tbsp, as here | 13 | 3 g |
| Pecan and oat topping, as here | 83 | 2 g |
| Mini marshmallows, 2 cups over the dish | 40 | 7 g |
| Mini marshmallows, 1 cup over the dish | 20 | 4 g |
| No topping | 0 | 0 g |
The filling sugar is the biggest lever. Taking a cup of brown sugar down to 2 tbsp saves 91 calories and 23 g of sugar on every plate, and the dish still tastes sweet, because the sweet potatoes do.
The sour cream is the third lever, and the only one the toggle above applies. Fat-free Greek yogurt in its place saves 21 calories and 3 g of fat a serving.
Marshmallows or pecans?
The honest answer surprises most people: marshmallows are the lighter topping. They are mostly air, so a cup of mini marshmallows weighs about 50 g, and 2 cups spread across the dish add about 40 calories a serving. The pecan and oat topping here is about 83.
What the pecans win on is sugar. The marshmallows add about 7 g a serving and the pecan topping about 2 g, with fat and a little fibre from the nuts instead. So pick the topping by the number you are watching: calories, marshmallows; sugar, pecans.
To make it with marshmallows instead, leave out the topping, bake the dish for 20 minutes, then scatter over 1 to 2 cups of mini marshmallows and give it another 8 to 10 minutes, until they are toasted. Watch it: they go from golden to burnt quickly.
Is honey or maple syrup healthier than brown sugar?
No. By the same volume, maple syrup carries about the same calories as brown sugar, and honey carries more, because it is denser. Per quarter cup, by USDA values and USDA’s own cup weights:
| Quarter cup of | Weight | kcal | Carbs |
|---|---|---|---|
| Brown sugar, packed | 55 g | 209 | 54 g |
| Maple syrup | 79 g | 205 | 53 g |
| Honey | 85 g | 258 | 70 g |
The only way honey saves anything is by using less of it. It is sweeter than sugar, the National Honey Board points out, so you can use less, and baking guides put that at about half to three quarters as much. Two thirds of a quarter cup comes to about 172 calories. The saving is the smaller quantity, not the honey. Use maple syrup or honey because you like the flavour, which is a fine reason on its own.
With no added sugar at all, leave the brown sugar out of the filling and keep the vanilla and cinnamon. The dish will taste of sweet potato rather than of dessert, which is what some people prefer at a table already carrying pie.
Can I make a diabetic-friendly sweet potato casserole?
You can make one with less sugar, but the carbohydrate is mostly the sweet potato itself. A serving of this recipe carries about 38 g of carbohydrate, and 28 g of that comes from the potato. Taking out every gram of added sugar removes about 5 g. So the portion does more than any swap: half a serving is half the carbohydrate.
How you cook the potato may matter too. In a Jamaican study of ten sweet potato varieties, boiled sweet potato had a glycaemic index of 41 to 50, against 82 to 94 baked and 79 to 93 roasted (Bahado-Singh and colleagues, 2011). That was ten healthy volunteers and one country’s varieties, and a Sri Lankan study found boiled sweet potatoes high, so treat it as a direction rather than a promise. It is one reason this recipe boils rather than roasts.
If you manage diabetes, fit a serving to the carbohydrate plan your care team has given you rather than to a label on a recipe, including this one.
What is the healthiest way to cook sweet potatoes?
Boiled or baked, the potato itself does not change much. USDA puts boiled sweet potato at 76 calories per 100 g and baked at 90, but that gap is water rather than a different potato: baking drives moisture off, so the same potato weighs less and each gram carries more.
Where they differ is the blood sugar response in the study above, which favours boiling, and the flavour, which favours the oven. Baked sweet potatoes caramelise at the edges and taste sweeter. In a casserole the oven browns the top anyway, so boiling the potatoes first gives up little.
High protein sweet potato casserole
It is a starchy side, and at about 5 g of protein a serving it will not become a high-protein dish without turning into something else. The swap adds about 1 g. Stirring another 200 g of fat-free Greek yogurt through the mash adds about 2.5 g a serving, and makes it tangier.
The honest place for protein on a Thanksgiving plate is the turkey. If you want the sides to pull more weight, the green bean casserole is the one to change: it carries 9 to 10 g a serving.
Where the calories are
Per serving, which is an eighth of the dish.
| Part of the dish | kcal | Protein | Carbs | Fat |
|---|---|---|---|---|
| Sweet potato, 140 g | 120 | 2 g | 28 g | 0 g |
| Pecans, 6.5 g | 45 | 1 g | 1 g | 5 g |
| Butter, mash and topping | 37 | 0 g | 0 g | 4 g |
| Sour cream, 15 g | 30 | 0 g | 1 g | 3 g |
| Brown sugar, mash and topping | 20 | 0 g | 5 g | 0 g |
| Rolled oats, 5 g | 19 | 1 g | 3 g | 0 g |
| Egg, a quarter | 18 | 1 g | 0 g | 1 g |
| Per serving | 289 | 5 g | 38 g | 13 g |
The potato is 120 calories of the 289, and nothing on this page changes it except the size of the spoon.
The swap, and what it is worth
| Swap | kcal | Protein | Carbs | Fat | Running total |
|---|---|---|---|---|---|
| Sour cream to fat-free Greek yogurt | −21 | +1 g | 0 g | −3 g | 268 kcal, 6 g protein |
In a hot sauce yogurt splits, because its proteins tighten with heat. Here it is mixed into a mash full of starch, which holds it the way a spoonful of cornstarch holds yogurt in a sauce, so it bakes without separating. The filling is a little tangier with yogurt, which the brown sugar and cinnamon carry well.
What goes wrong
A watery casserole. Boiled sweet potatoes hold water on the outside, and it ends up in the dish. Dry them in the hot pan for a minute after draining.
A gluey filling. A food processor overworks the starch. Mash by hand or with a hand mixer and stop once it is smooth.
Scrambled egg in the mash. The mash was too hot. Five minutes of cooling is enough.
A burnt topping. Pecans and sugar darken fast. The foil goes on as soon as the nuts look mahogany rather than golden.
Making it ahead
Make the filling up to a day ahead, spread it in the dish, cover it and keep it in the fridge, with the topping mixed and stored separately. Scatter the topping on just before baking, and add about 10 minutes to the time, since it goes in cold.
Leftovers keep 3 to 4 days in the fridge, the USDA guidance for leftovers. The filling freezes well without the topping, and the same guidance gives 3 to 4 months in the freezer.
A note for American shops: orange sweet potatoes are often sold as yams. True yams are a different, starchier plant, and this recipe wants the orange sweet potato, whatever the sign above it says.
Every figure here is an estimate from USDA values rather than a measurement. Why recipe macros are estimates explains how far they move with what you buy.
Where next
This recipe is one of the dishes in How to thicken gravy, and the ratio for each way.
Worth cooking next:
- Healthy green bean casserole, and what the can of soup really costsCampbell's classic is 151 calories and 3 g of protein a serving. This one comes to about 199, with three times the protein and a third of the sodium.
- Lighter mashed potatoes that are still worth eatingGreek yogurt for the sour cream keeps mash creamy and adds protein. Why floury potatoes and warm milk matter more to the texture than the fat does.
- Healthy spinach artichoke dip, and where the calories were hidingThree swaps take spinach artichoke dip from about 289 calories a serving to 135, and the fat from 25 g to 7 g. What each swap is worth, and what goes wrong.
Cooking it as part of a week? ReciPop plans seven days of meals around the time you have, the appliances you own and how many you are feeding, then turns them into one grocery list sorted by aisle. How the weekly plan works