This Sweet Potato Casserole features roasted sweet potatoes, fresh rosemary, a crunchy panko-graham crumb topping and gooey marshmallows—perfect for the holidays.
The pairing of sweet potatoes and rosemary gives this side dish a bright, festive flavor. Roasting the potatoes in olive oil concentrates their natural sweetness while the fresh rosemary adds an herbal note that balances the brown sugar and marshmallows.
This Thanksgiving-friendly casserole uses roasted sweet potatoes mashed with cinnamon, brown sugar and a splash of half-and-half, then finished with a crunchy topping made from panko crumbs, crushed graham crackers, butter and rosemary. Mini marshmallows add a nostalgic, melty finish.
Ingredients
- Roasted sweet potatoes – sweet potatoes tossed with olive oil, salt and fresh rosemary.
- Panko breadcrumbs & crushed graham crackers – provide a crisp, crunchy topping.
- Fresh rosemary – use minced fresh rosemary for the best flavor; optional if you prefer a simpler dish.
- Half-and-half – can be substituted with milk or heavy cream for a richer texture.
- Light brown sugar – brings caramel notes; granulated sugar can be used in a pinch.
- Mini marshmallows – for the classic sweet, melty topping.
- Butter – cold and cubed for the crumb topping.
How to make sweet potato casserole
1. Roast the sweet potatoes. Preheat the oven to 425°F. Peel 5 medium sweet potatoes and cut into 1-inch pieces. Toss with 1/4 cup olive oil, 1 teaspoon minced fresh rosemary and 1/2 teaspoon salt. Spread on a baking sheet and roast for about 30 minutes, until tender and slightly caramelized.
2. Prepare the crumb topping. In a medium bowl combine 1 cup panko breadcrumbs, 1/2 cup crushed honey graham crackers, 1/4 cup light brown sugar, 4 tablespoons cold butter cut into small cubes and the remaining 1 teaspoon minced rosemary. Use a pastry cutter or fork to cut the butter into the dry ingredients until the mixture is crumbly and evenly mixed.
3. Mash and assemble. Reduce the oven temperature to 350°F. Transfer the roasted sweet potatoes to a large bowl and mash with a hand masher or fork until mostly smooth but still slightly chunky. Stir in 1/3 cup light brown sugar, 1/8 teaspoon cinnamon and 2 tablespoons half-and-half (or a milk/cream substitute). Spread the mashed sweet potatoes evenly into an 8″ x 8″ baking dish.
4. Top and bake. Scatter 2 cups mini marshmallows over the mashed sweet potatoes, then sprinkle the panko-graham crumb topping evenly on top. Bake at 350°F for about 30 minutes, or until the casserole is heated through, the marshmallows are melted and the topping is golden brown.
5. Serve and store. Let the casserole rest a few minutes before serving so the topping sets slightly. Store leftovers covered in the refrigerator for up to 4 days. You can assemble the dish a day ahead and bake it when you’re ready to serve.
Recipe details
- Prep time: 20 mins
- Cook time: 1 hr
- Total time: 1 hr 20 mins
- Servings: 6
- Calories: Approximately 521 kcal per serving
Ingredients (full list)
- 5 medium sweet potatoes
- 1/4 cup olive oil
- 2 teaspoons minced fresh rosemary, divided
- 1/2 teaspoon salt
- 1/3 cup light brown sugar (for the potatoes)
- 1/8 teaspoon cinnamon
- 2 tablespoons half-and-half (milk or heavy cream can be substituted)
- 4 tablespoons cold butter, cubed (for the topping)
- 1 cup Panko breadcrumbs
- 1/2 cup crushed honey graham crackers
- 1/4 cup light brown sugar (for the topping)
- 2 cups mini marshmallows
Instructions (summary)
- Preheat oven to 425°F. Peel and cut sweet potatoes into 1-inch pieces, toss with olive oil, 1 tsp rosemary and salt. Roast 30 minutes.
- Remove potatoes, transfer to a bowl and lower oven to 350°F.
- Mash potatoes until mostly smooth; stir in 1/3 cup brown sugar, cinnamon and half-and-half. Spread into an 8″x8″ baking dish.
- In a medium bowl combine remaining 1 tsp rosemary, butter, panko, crushed graham crackers and 1/4 cup brown sugar; cut butter into mixture.
- Top potatoes with marshmallows and crumb topping. Bake 30 minutes or until topping is golden and marshmallows are melted.
Notes
- Store covered in the fridge for up to 4 days.
- Can be assembled a day in advance and baked just before serving.
Originally posted November 2014; recipe instructions updated November 2019.