Sweet Potato Casserole

This low-FODMAP sweet potato casserole tops a maple-sweetened, portion-capped sweet potato mash with a gluten-free pecan streusel.

Prep 20 min

Cook 30 min

Serves 8

Gluten-freeVegetarian

Ingredients

For the filling:

• 600g (about 1.3 lb) orange sweet potato, peeled and cut into 1-inch cubes (portions to about 75g cooked per serving)
• 2 tablespoons (30g) unsalted butter
• 3 tablespoons (45ml) lactose-free milk
• 2 tablespoons (30ml) pure maple syrup
• 1 large egg, lightly beaten
• 1 teaspoon vanilla extract
• 3/4 teaspoon ground cinnamon
• 1/4 teaspoon ground nutmeg
• 1/4 teaspoon salt

For the pecan topping:

• 1/2 cup (60g) pecans, roughly chopped
• 1/4 cup (30g) gluten-free 1:1 flour blend
• 1/4 cup (50g) packed light brown sugar
• 2 tablespoons (30g) cold unsalted butter, cut into small cubes
• Pinch of salt

Instructions

Cook the Sweet Potato

1. Heat the oven to 375°F (190°C). Lightly grease an 8-inch square baking dish or a similar 6-cup dish.
2. Put the sweet potato cubes in a saucepan, cover with water, and boil until fork-tender, 12 to 15 minutes. Drain well and return to the pan for a minute to steam off any extra water.

Make the Filling

1. Mash the sweet potato with the butter, lactose-free milk, maple syrup, cinnamon, nutmeg, and salt until smooth.
2. Let it cool for about 5 minutes so it won't cook the egg, then stir in the beaten egg and vanilla.
3. Spread the mash evenly into the prepared dish.

Top and Bake

1. In a small bowl, stir together the pecans, flour, brown sugar, and salt. Add the cold butter and rub it in with your fingertips until the mix looks like coarse crumbs.
2. Scatter the topping over the sweet potato.
3. Bake for 25 to 30 minutes, until the topping is golden and the filling is set (an egg-based dish is done at 160°F / 71°C). Rest 5 to 10 minutes before serving.

Tips & Substitutions

• Keep the sweet potato to 75g per serving. Monash rates orange sweet potato low-FODMAP at 75g cooked; above that it carries enough mannitol to bother sensitive guts. Splitting this dish into 8 keeps each portion at the tested serve.
• Skip the marshmallows. Marshmallows add fructose and don't help the FODMAP load. The pecan streusel gives you the sweet, crunchy top without them.
• Make it egg-free. Leave out the egg and stir 1 tablespoon of the GF flour blend into the warm mash instead. It sets a little softer but slices fine after resting.
• Watch the pecan portion. Pecans are low-FODMAP at about 20g (roughly 10 halves) per serving. This recipe uses less than that per portion, so there's room if someone goes back for a little more.
• Swap to walnuts if you prefer. Walnuts work in the topping at a similar amount. Keep to Monash's tested nut serve and check the app for the current number.
• For a dairy-free version. Use a plant-based block butter and a low-FODMAP milk like almond or a lactose-free oat milk in place of the dairy. The topping still crisps.

Why This Works

Sweet potato stays under the mannitol cap. Portioning to 75g cooked per serve keeps this in Monash's green range; larger heaps are where the polyol adds up.

Maple syrup instead of honey. Honey is high in excess fructose. Maple syrup is low-FODMAP in normal amounts and gives the same warm sweetness.

A pecan topping in a small dose. Pecans test low-FODMAP at about 20g per serving, so a light scatter across the top keeps every portion comfortable.

Gluten-free flour in the streusel. Wheat flour brings fructans. A GF 1:1 blend (one without added inulin or chicory root) binds the crumb without them.

Storage

Cover and refrigerate leftovers for up to 3 to 4 days. Reheat individual portions in the microwave, or warm the whole dish covered in a 350°F (175°C) oven until hot. It freezes for up to 2 months; thaw overnight in the fridge before reheating, though the topping softens a little. Keep to one 75g sweet potato portion per serving when you plate it back up, and check the Monash app for current tested serving sizes.

Not sure about an ingredient? The FODMAP Foods app rates 1,000+ foods low, moderate, or high FODMAP, with the safe portion for each, so you can cook with confidence.