This Sweet Potato Casserole combines roasted sweet potatoes, fresh rosemary, a crunchy panko-graham crumb, and gooey marshmallows for a memorable holiday side.
The earthy brightness of rosemary paired with sweet potatoes gives this dish a festive, savory-sweet flavor. Roasting the potatoes in olive oil concentrates their sweetness and adds a caramelized depth, while the crumb topping adds texture and the marshmallows bring that classic, indulgent finish.
This casserole is simple to prepare and perfect for Thanksgiving or any holiday table: roasted sweet potatoes mashed with warm spices and cream, topped with mini marshmallows and a crisp panko-and-graham crumb mixture, then baked until bubbly and golden.
Ingredients
- Roasted Sweet Potatoes – Sweet potatoes cut into pieces, tossed with olive oil, salt, and fresh rosemary, then roasted.
- Panko Bread Crumbs & Graham Crackers – Combine for a crunchy, sweet-savory topping.
- Rosemary – Use fresh and finely minced for the best aromatic flavor; optional if preferred.
- Half-and-Half – Provides creaminess; milk or heavy cream may be substituted.
- Light Brown Sugar – Adds caramel-like sweetness; granulated sugar can be used instead.
- Marshmallows – Mini marshmallows give the casserole its signature sweet, melty layer.
- Butter – Cold, cubed butter is cut into the crumb topping for flakiness and richness.
How to make sweet potato casserole
Roast the sweet potatoes. Preheat the oven to 425°F. Peel and dice sweet potatoes into roughly 1-inch pieces. Toss with olive oil, 1 teaspoon minced fresh rosemary, and salt. Spread on a baking sheet and roast for about 30 minutes, until tender and lightly caramelized.
Prepare the crumb topping. In a medium bowl combine the remaining 1 teaspoon minced rosemary, cold cubed butter, panko bread crumbs, crushed honey graham crackers, and light brown sugar. Use a pastry cutter or a fork to cut the butter into the dry ingredients until the mixture holds together in coarse crumbs.
Assemble the casserole. Reduce oven temperature to 350°F. Transfer the roasted sweet potatoes to a large bowl and mash with a potato masher or fork until mostly smooth with a few small chunks remaining. Stir in 1/3 cup light brown sugar, 1/8 teaspoon cinnamon, and 2 tablespoons half-and-half (or substitute). Mix until combined and spread the mash evenly into an 8″ x 8″ baking dish.
Top and bake. Evenly scatter 2 cups mini marshmallows over the sweet potato layer, then sprinkle the panko-graham crumb mixture on top. Bake at 350°F for about 30 minutes, or until heated through and the topping is golden and the marshmallows are melted and lightly toasted.
Serve and store. Let the casserole rest a few minutes before serving so the topping sets slightly. Store any leftovers covered in the refrigerator for up to 4 days. This dish can also be assembled a day ahead and baked just before serving for convenience.
Recipe notes:
- Store covered in the fridge for up to 4 days.
- You can assemble the casserole a day in advance, keep it refrigerated, and bake when ready to serve.
- For a dairy-free version, substitute your preferred non-dairy milk and margarine, and omit marshmallows if they contain gelatin.
Sweet Potato Casserole
Ingredients
- 5 medium sweet potatoes
- ¼ cup olive oil
- 2 teaspoons minced fresh rosemary
- ½ teaspoon salt
- ⅓ cup light brown sugar
- ⅛ teaspoon cinnamon
- 2 tablespoons half and half (milk or heavy cream can be substituted)
- 4 tablespoons butter (cold, cut into small cubes)
- 1 cup Panko bread crumbs
- ½ cup honey graham crackers (crushed)
- ¼ cup light brown sugar
- 2 cups mini marshmallows
Instructions
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Preheat oven to 425°F. Peel sweet potatoes and cut into 1-inch pieces. Toss on a baking sheet with olive oil, 1 teaspoon minced rosemary, and salt. Bake for 30 minutes until tender.
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Remove from oven and transfer potatoes to a large bowl. Reduce oven temperature to 350°F.
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Mash potatoes until mostly smooth with a few small chunks. Stir in ⅓ cup light brown sugar, ⅛ teaspoon cinnamon, and 2 tablespoons half-and-half. Spread evenly into an 8″ x 8″ baking dish.
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In a medium bowl combine remaining 1 teaspoon minced rosemary, cold butter cubes, panko crumbs, crushed graham crackers, and ¼ cup light brown sugar. Cut the butter into the mixture until crumbly.
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Top the sweet potatoes with 2 cups mini marshmallows and the crumb topping. Bake at 350°F for about 30 minutes, until the topping is golden and the marshmallows are melted and lightly browned.
Notes
- Store covered in the fridge for up to 4 days.
- Can be assembled one day in advance, refrigerated, and baked when ready to serve.
Originally posted in November 2014 and updated in November 2019 with clarified instructions.