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Creamy roasted sweet potato with a hint of vanilla, baked under a buttery brown sugar and pecan streusel. This is the classic American Thanksgiving side, and it’s just as good next to a Christmas roast.
Nicky’s Notes
Sweet potato casserole is one of the big Thanksgiving sides in the US, but here in the UK it’s pretty much unheard of. Sweet potato and sugar with a crunchy pecan topping, served next to the turkey? I wasn’t sure either.
Then I tried it, and I’ve been completely swayed. The sweet potato is soft and creamy, the topping is buttery and crunchy, and it’s lovely with salty gravy and roast turkey.
I’m not quite ready for the marshmallow version yet though. A pecan streusel feels like a good place to start!
What makes it so good:
- Sweet, but not dessert. There’s just 2 tablespoons of brown sugar in the sweet potato itself, so you can still taste the sweet potato. Most of the sweetness is in the topping.
- Roasted, not boiled. Roasting the sweet potatoes whole concentrates their flavour and keeps the mash thick and creamy instead of watery.
- Big crunchy pecan clusters. I keep the pecans whole, so they toast as the casserole bakes and you get proper crunch in every scoop.
- A pinch of flaky salt. It goes on right at the end and cuts through the sweetness of the topping.
- Very little hands-on time. The sweet potatoes roast while you get on with everything else, then it’s a quick mash and mix.
Table of Contents
📋 Ingredients for Sweet Potato Casserole
***Full recipe with detailed quantities in the recipe card below***
A few notes on the key ingredients, including what to look for if you’re in the US:
- Sweet potatoes: Go for the orange-fleshed ones. Try to pick potatoes of a similar size so they roast at the same rate. I use about 7 small or 5 medium for 1kg (2.2lbs).
- Double cream: This is heavy cream in the US. It makes the mash rich and silky.
- Egg: Just one, and it helps the sweet potato set a little in the oven, so it scoops out neatly rather than spreading across the plate. A UK medium egg is about the same as a US large egg.
- Pecan halves: I leave them whole in the streusel. They toast as the casserole bakes and give you proper crunchy clusters on top. You can roughly chop them if you’d like smaller pieces.
- Plain flour: All-purpose flour in the US. Mixed with the melted butter and sugar, it’s what turns the topping clumpy and crisp.
- Flaky sea salt: I use Maldon. A small sprinkle over the finished casserole balances the sweetness of the topping.
🧑🍳 Abbreviated Recipe
***Full recipe with detailed steps in the recipe card below***
Roast the sweet potatoes whole until soft, then scoop out the flesh and mash with butter, cream, egg, sugar, vanilla and salt. Spread in a baking dish. For the streusel, mix the flour, brown sugar, cinnamon, salt and pecans, then stir in melted butter until it goes clumpy. Spoon it over the sweet potato.
Bake until golden, then finish with a sprinkle of flaky sea salt.
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- Let the sweet potato cool before adding the egg. If the flesh is still piping hot, the egg can start to cook and you’ll get little scrambled bits in the mash.
- Keep an eye on it towards the end. Brown sugar and pecans go from golden to too dark quite quickly. A loose sheet of foil over the top for the last few minutes sorts it out.
Make ahead and Leftovers Guide
- Make Ahead (up to 1 day ahead): Make the sweet potato base, spread it in the dish, cover and keep it in the fridge. Mix the streusel and keep it in a separate container in the fridge.
- On the day: Spoon the streusel over the cold base and bake as normal. Because it’s going in fridge-cold, it may need an extra 5 to 10 minutes. It’s ready when it’s hot all the way through and golden on top.
- Leftovers: Cool any leftovers, cover and keep in the fridge for up to 3 days. Reheat covered with foil at 160C fan/180C/350F/gas 4 for about 15 to 20 minutes, until piping hot. The topping softens a little in the fridge, so taking the foil off for the last 5 minutes helps it crisp up again.
- Freezing Leftovers: Divide leftovers into individual servings and place them into airtight, freezer-safe containers or zip-top freezer bags and freeze (up to 3 months).
- Defrost overnight in the refrigerator.
- Air fryer reheat (1 portion): Place a portion on parchment and heat at 160C/325F for 4 to 6 minutes, until warmed through. Check after 3 minutes, and if the pecans are getting dark, cover with a small piece of foil tucked underneath so it can’t blow about.
- Oven reheat (1 portion): Put a portion in a small dish, cover loosely with foil and heat at 160C fan/180C/350F/gas 4 for 10 to 12 minutes. Uncover for the last 2 minutes to crisp the topping.
Sweet Potato Casserole Recipe
Equipment
Ingredients
Sweet potato base:
- 1 kg (2.2lbs) sweet potatoes (try to ensure they're even sizes – I use about 7 small or 5 medium sweet potatoes)
- 60 g (4 tbsp) unsalted butter
- 60 ml (4 tbsp) double (heavy) cream
- 1 medium egg (large in the USA)
- 2 tbsp light brown sugar
- 1 tsp vanilla extract
- ¼ tsp salt
Pecan streusel topping:
- 60 g (1/2 cup) plain (all purpose) flour
- 100 g (1/2 cup) light brown sugar
- ½ tsp ground cinnamon
- Pinch of salt
- 200 g (2 cups) pecan halves
- 60 g (4 tbsp) unsalted butter, melted
To serve:
- Maldon salt flakes (or other flaky sea salt)
Instructions
- Preheat the oven to 200C fan/220C/425F/gas 7.
- Prick the potatoes several times and place on a baking tray lined with parchment.1 kg (2.2lbs) sweet potatoes
- Roast for 45-60 minutes, until the potatoes are tender (a knife should slice into them easily). Allow to cool for 15 minutes (or until cool enough to handle).
- Reduce the oven temperature to 180C fan/200C/400F/gas 6.
- Slice the potatoes in half and scoop out the flesh into a bowl.
- Add the butter, cream, egg, sugar, vanilla extract and salt and mash or whisk together until light and smooth.60 g (4 tbsp) unsalted butter, 60 ml (4 tbsp) double (heavy) cream, 1 medium egg, 2 tbsp light brown sugar, 1 tsp vanilla extract, ¼ tsp salt
- Transfer to a greased 23cm (9 inch) round baking dish (this is around 2.6 litres/2.75 quarts using a dish with a 6cm/2.5-inch depth) and level out with a spoon.
- Now make the streusel. Add the flour, sugar, cinnamon, salt and pecans to a bowl and mix together.60 g (1/2 cup) plain (all purpose) flour, 100 g (1/2 cup) light brown sugar, ½ tsp ground cinnamon, Pinch of salt, 200 g (2 cups) pecan halves
- Pour over the melted butter and stir it in, until the mixture goes clumpy, with no flour bits remaining.60 g (4 tbsp) unsalted butter, melted
- Spoon over the sweet potatoes evenly.
- Place in the oven and bake for 25-30 minutes, until the top is golden. If it starts to look too dark towards the end, you can cover with foil for the last 5-10 minutes.
- Rest for 5 minutes, then sprinkle with a little salt and serve.Maldon salt flakes
Notes
Baking dish size
I use a 23cm (9 inch) round dish, 6cm (2.5 inches) deep, which holds about 2.6 litres (2.75 quarts). A 9 x 13 inch dish also works, but the layer will be thinner, so start checking after 20 minutes, as it will cook a little faster.Sweet Potatoes
Pick sweet potatoes of a similar size so they cook evenly. If some are smaller, check them with a knife and take them out as they soften.Are sweet potatoes and yams the same thing?
Not quite. True yams are a different vegetable, but in many US supermarkets orange-fleshed sweet potatoes are sold as yams. Those are the ones you want for this recipe. Can I add marshmallows? I haven’t tried it myself yet, but topping it with mini marshmallows is a really popular way to serve it in the US. Sprinkle on mini marshmallows for the last 5 minutes in the oven and keep a close eye on them as they can burn quickly. Five minutes should be ok to get them to puff up and turn golden.Make ahead
Make the sweet potato base up to 1 day ahead, cover and chill in the dish. Keep the streusel in a separate container in the fridge. Top and bake on the day, adding 5 to 10 minutes as it goes in cold.Leftovers
Keep covered in the fridge for up to 3 days. Reheat covered with foil at 160C fan/180C/350F/gas 4 for 15 to 20 minutes, until piping hot. Nutritional information is approximate, per serving, based on this recipe serving 10 people.Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
🍽️ What to serve it with
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