- Prep
- 20 min
- Cook
- 45 min
- Total
- 65 min
- Serves
- 8
Ingredients
What you’ll need — tap to tick off as you go
- 1 ⅜ kg
- 60 g
- 60 g
- 120 ml
- 1 tsp
- 1 tsp
- ¼ tsp
- ½ tsp
- 100 g
- 50 g
- 45 g
- 80 g
Process
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Preheat the oven to 190°C. Butter a 23 x 33 cm baking dish.
Put the sweet potatoes in a large pot, cover with cold water by 3 cm, and add a generous pinch of fine salt. Bring to a boil, then reduce to a steady simmer and cook for 15–20 minutes, until a knife slides in with no resistance. Drain well and return the potatoes to the hot pot for 2 minutes to steam dry.
Mash the sweet potatoes until completely smooth, or pass them through a ricer. Stir in 60 g melted unsalted butter, 40 g brown sugar, the eggs, warm whole milk, vanilla extract, ground cinnamon, ground nutmeg, and 0.5 tsp fine salt. Mix until glossy and uniform.
Spread the sweet potato mixture evenly in the prepared baking dish.
In a bowl, combine the pecans, all-purpose flour, and remaining 20 g brown sugar. Add the cold cubed unsalted butter and rub it in with your fingertips until the mixture looks like coarse breadcrumbs.
Scatter the pecan streusel evenly over the sweet potatoes. Bake for 25 minutes, until the topping is golden and the edges bubble.
If using mini marshmallows, scatter them over the top and bake for 5–7 minutes more, until puffed and lightly toasted. Let the casserole rest for 10 minutes before serving.
Kitchen notes
Kitchen notes
- The most common mistake is undercooking the sweet potatoes, which leaves a watery, fibrous mash. Boil until a knife meets zero resistance, then let them steam dry in the drained pot so excess moisture evaporates.
- Do not overmix after adding the eggs, or the casserole can turn gluey. Fold just until the mixture is uniform.
- For the crispest streusel, keep the butter for the topping cold and work quickly with your fingertips; warm butter makes a paste that bakes dense instead of crunchy.
- If you add marshmallows, watch them closely in the final minutes. They go from toasted to burnt in under a minute under a hot grill element.
Substitutions
- whole milk→canned coconut milk (for a dairy-free version)
- pecans→walnuts or almonds
- all-purpose flour→gluten-free all-purpose flour blend
- brown sugar→coconut sugar
- eggs→2 tbsp ground flaxseed mixed with 6 tbsp water, rested 10 minutes
Storage & reheating
Cool completely, then store in an airtight container in the fridge for up to 4 days. To reheat, cover with foil and warm in a 160°C oven for 15-20 minutes, or microwave individual portions on high for 1-2 minutes. For longer storage, wrap tightly and freeze for up to 2 months; thaw overnight in the fridge before reheating. Do not freeze the marshmallow topping, as it becomes sticky and grainy.
FAQ
The questions we get asked most
Why is my sweet potato casserole watery?
The sweet potatoes were likely undercooked or not drained well enough. Boil them until a knife slides in with no resistance, then return them to the dry hot pot for a couple of minutes to steam off excess moisture. Also avoid adding extra liquid beyond the recipe, and let the casserole rest for 10 minutes after baking so it sets.
Can I make sweet potato casserole ahead of time?
Yes. Assemble the casserole up to 24 hours in advance, cover, and refrigerate. Add the streusel just before baking so it stays crisp. You can also boil and mash the sweet potatoes up to 2 days ahead and keep them in the fridge, then stir in the eggs, milk, and seasonings on the day of baking.
Can I use canned sweet potato or yam puree instead of fresh?
Yes. Substitute about 1.2 kg of canned puree, drained well, for the fresh sweet potatoes. Skip the boiling step and simply warm the puree slightly so it mixes smoothly with the butter and eggs. Canned puree is often looser, so you may need to bake the casserole 5-10 minutes longer to firm it up.
How do I know when the casserole is done?
The edges should bubble and the center should look set rather than wet when you gently shake the dish. The streusel will be golden brown. If you added marshmallows, they should be puffed and toasted. A knife inserted in the center should come out clean, and the casserole will firm up further as it rests.
Can I make this sweet potato casserole without eggs?
Yes. Replace the eggs with 2 tablespoons of ground flaxseed mixed with 6 tablespoons of water and left to thicken for 10 minutes. The casserole will be slightly softer but still holds together. Alternatively, use 3 tablespoons of aquafaba per egg and reduce the milk by 1 tablespoon.
Why did my pecan topping turn soggy?
The streusel was probably added too far in advance or the butter was too warm. Keep the topping butter cold, scatter the streusel just before baking, and do not cover the dish with foil during baking, which traps steam. If making ahead, refrigerate the unbaked streusel separately and add it right before the oven.
Can I freeze sweet potato casserole?
Yes, but freeze it before adding marshmallows. Wrap the baked and cooled casserole tightly and freeze for up to 2 months. Thaw overnight in the fridge, then reheat covered at 160°C for 20-25 minutes. If you want marshmallows, add them after reheating and broil for 2-3 minutes until toasted.
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