Sweet Potato Casserole with Pecan Streusel or Marshmallows

Why You’ll Love This Recipe

• Whipped sweet potatoes turn incredibly silky, with warm spices and just-right sweetness.
• Choose your crown: buttery pecan streusel for crunch or toasty marshmallows for campfire nostalgia.
• Roasting concentrates flavor, so the casserole tastes rich without being heavy.
• Great make-ahead friendly side that travels well for holidays and potlucks.

Grocery List

• Produce: Sweet potatoes (3 lb)
• Dairy: Unsalted butter, heavy cream or half-and-half, eggs
• Pantry: Light brown sugar, vanilla extract, ground cinnamon, ground nutmeg, kosher salt, all-purpose flour, pecans (or mini marshmallows)

Full Ingredients

Whipped Sweet Potato Base

• 3 lb sweet potatoes (about 4 large)
• 6 tbsp unsalted butter, melted (85 g)
• 1/2 cup light brown sugar, packed (100 g)
• 1/4 cup heavy cream or half-and-half (60 ml)
• 2 large eggs, at room temperature
• 1 tsp pure vanilla extract
• 1 tsp ground cinnamon
• 1/4 tsp ground nutmeg
• 1/4 tsp kosher salt

Pecan Streusel Topping (Option)

• 1 cup pecans, chopped (110 g)
• 1/2 cup all-purpose flour (65 g)
• 1/2 cup light brown sugar, packed (100 g)
• 1/2 tsp ground cinnamon
• 1/4 tsp kosher salt
• 4 tbsp unsalted butter, melted (57 g)

Toasted Marshmallow Topping (Option)

• 3 cups mini marshmallows (150 g)

Step-by-Step Instructions

Step 1: Roast the sweet potatoes

Preheat the oven to 425°F (220°C). Line a baking sheet with foil for easy cleanup. Scrub the sweet potatoes, prick them several times with a fork, and place on the sheet. Roast for 55–65 minutes, turning once, until the skins are wrinkled and a knife slides through the center with no resistance. Tip: Halved potatoes roast a bit faster (45–55 minutes), cut-side down.

Step 2: Reduce oven heat and prep the dish

Lower the oven temperature to 350°F (175°C). Lightly grease a 2 1/2– to 3-quart baking dish (such as a 9×13-inch). Let the potatoes cool just until you can handle them comfortably.

Step 3: Scoop, whip, and season

Split the potatoes and scoop the flesh into a large mixing bowl; you should have about 4 1/2 to 5 cups. Add melted butter, brown sugar, cream, eggs, vanilla, cinnamon, nutmeg, and salt. Using a hand mixer on medium speed (or a sturdy whisk), beat for 1–2 minutes until smooth, fluffy, and well combined. Taste and adjust salt or spice to preference. Spread the mixture evenly into the prepared baking dish, smoothing the top.

Step 4: Make the pecan streusel (if using)

In a medium bowl, combine pecans, flour, brown sugar, cinnamon, and salt. Drizzle in melted butter and stir with a fork until large, moist clumps form. If you plan to do half streusel and half marshmallows, keep half the surface bare and sprinkle streusel over the other half.

Step 5: Choose your topping path

For streusel only: Sprinkle the streusel evenly over the entire surface. For marshmallows only: Leave the surface plain for now; marshmallows go on later. For a half-and-half casserole: Top one side with streusel and leave the other side plain, keeping a small uncovered gap between sections so the toppings don’t bleed into each other.

Step 6: Bake to set and caramelize

Streusel version: Bake at 350°F (175°C) for 25–30 minutes until the casserole is just set and the topping is golden and crisp. Marshmallow version: Bake the plain casserole for 20 minutes, then remove, scatter mini marshmallows in an even layer, and return to the oven for 8–10 minutes until puffed and golden. For extra color, broil 30–60 seconds, watching closely to avoid burning.

Step 7: Rest and serve

Let the casserole rest 10 minutes before serving so it slices cleanly. If desired, sprinkle the streusel side with a few extra chopped pecans, or dust the marshmallow side with a whisper of cinnamon. Serve warm.

Pro Tips

• Roasting beats boiling: it concentrates sweetness and prevents a watery casserole.
• Use room-temperature eggs to help the mixture blend smoothly and bake evenly.
• For ultra-smooth texture, pass the roasted potatoes through a ricer before mixing.
• Make half-and-half: divide the topping so guests can choose pecan crunch or gooey marshmallow.
• Watch the broiler like a hawk—marshmallows go from golden to burnt in seconds.

Variations

• Maple-bourbon: Replace 2 tbsp brown sugar with 2 tbsp pure maple syrup and add 1–2 tbsp bourbon to the potato base.
• Orange spice: Add 1 tsp orange zest and 1/4 tsp ground ginger to the base for a bright, aromatic twist.
• Dairy-free: Use coconut cream (1/4 cup) and a plant-based butter; omit eggs and add 1 tbsp cornstarch to help set.

Storage & Make-Ahead

Assemble up to 2 days in advance (through Step 3). Cover and refrigerate. Add streusel or marshmallows just before baking. Bake from cold at 350°F (175°C) for 30–35 minutes (streusel) or 25 minutes + 8–10 minutes for marshmallows. Leftovers keep refrigerated, covered, for 4 days; reheat at 325°F (165°C) until warmed through. The whipped base freezes well (without toppings) for up to 2 months; thaw overnight in the fridge, stir, spread in a dish, then top and bake.

Nutrition (per serving)

Approximate for 10 servings. With pecan streusel: 420 kcal; 6 g protein; 25 g fat; 46 g carbs; 3 g fiber; 260 mg sodium. With marshmallows (no streusel): 300 kcal; 5 g protein; 10 g fat; 49 g carbs; 3 g fiber; 220 mg sodium. Nutrition will vary with brands and exact portion size.