This sweet potato casserole combines roasted sweet potatoes, fresh rosemary, a crunchy panko and graham crumb topping, and a cloud of marshmallows for a memorable holiday side dish.
Sweet potatoes and rosemary are a surprisingly perfect pairing: the herb brings a savory, aromatic counterpoint to the natural sweetness of the potatoes. This Thanksgiving-ready casserole uses sweet potatoes that are first roasted in olive oil with fresh rosemary and salt, then mashed with brown sugar, cinnamon and a touch of half-and-half. A crisp topping made from Panko bread crumbs, crushed honey graham crackers and cold butter adds texture, while mini marshmallows on top provide the classic, nostalgic finish.
Key Features
- Roasted sweet potatoes for concentrated, caramelized flavor
- Fresh rosemary for a savory herbal note
- Panko and graham cracker topping for a contrast of crunch and sweetness
- Mini marshmallows for a golden, melty finish
- Can be assembled a day ahead and refrigerated for easy holiday timing
Ingredients
- Roasted Sweet Potatoes: 5 medium sweet potatoes, olive oil, salt and fresh rosemary.
- Panko Bread Crumbs and Graham Crackers: For a crunchy, slightly sweet topping.
- Fresh Rosemary: Finely minced for the potatoes and the topping; optional but recommended.
- Half-and-Half: Adds creaminess; can substitute milk or heavy cream.
- Light Brown Sugar: Used in the sweet potato mash and the crumb topping; gives a molasses note.
- Mini Marshmallows: For the top layer and that classic casserole finish.
- Butter: Cold and cubed, to be cut into the crumb mixture for flakiness and flavor.
How to make sweet potato casserole
1. Roast the sweet potatoes. Preheat the oven to 425°F. Peel the sweet potatoes and cut into 1-inch pieces. Toss the pieces with about 1/4 cup olive oil, 1 teaspoon minced fresh rosemary and 1/2 teaspoon salt. Spread in a single layer on a baking sheet and roast for approximately 30 minutes, until tender and slightly caramelized at the edges.
2. Prepare the topping. In a medium bowl combine 1 cup Panko bread crumbs, 1/2 cup crushed honey graham crackers, 1/4 cup light brown sugar, 4 tablespoons cold butter cut into small cubes and 1 teaspoon minced fresh rosemary. Use a pastry cutter or fork to cut the butter into the dry ingredients until the mixture resembles coarse crumbs. Refrigerate until ready to use so the butter stays cold and creates a crunchy texture when baked.
3. Mash and season the sweet potatoes. When the roasted potatoes are tender, remove them from the oven and reduce the oven temperature to 350°F. Transfer the potatoes to a large bowl and mash with a potato masher or fork until mostly smooth but with a little texture remaining. Add 1/3 cup light brown sugar, 1/8 teaspoon cinnamon and 2 tablespoons half-and-half (or a splash of milk or cream). Stir gently to combine and taste, adjusting salt or sugar as needed.
4. Assemble the casserole. Spread the mashed sweet potatoes evenly into an 8″ x 8″ baking dish. Sprinkle 2 cups mini marshmallows evenly over the top, then distribute the chilled crumb topping across the marshmallows. The crumb layer will brown and the marshmallows will melt and puff slightly during baking for a pleasing contrast of textures.
5. Bake. Bake the casserole at 350°F for about 30 minutes, or until the casserole is heated through and the topping is melted and golden brown. If you prefer more browning on the marshmallows, place briefly under the broiler for 1–2 minutes, watching closely so they don’t burn.
Recipe Details
- Prep time: about 20 minutes
- Cook time: about 1 hour (including roasting and final bake)
- Total time: about 1 hour 20 minutes
- Servings: 6
- Calories: approximately 521 kcal per serving (estimate)
- Course: Side dish
- Cuisine: American
Instructions (Step-by-step)
- Preheat oven to 425°F. Peel and cut sweet potatoes into 1″ pieces. Toss with olive oil, 1 tsp minced rosemary and salt. Roast for 30 minutes.
- Remove potatoes and transfer to a large bowl. Reduce oven to 350°F.
- Mash the sweet potatoes until nearly smooth, leaving a little texture. Stir in 1/3 cup light brown sugar, 1/8 tsp cinnamon and 2 tbsp half-and-half. Spread in an 8″ x 8″ baking dish.
- Make the topping by combining remaining 1 tsp minced rosemary, cold butter cubes, Panko, crushed graham crackers and 1/4 cup light brown sugar; cut butter in until crumbly.
- Top the sweet potatoes with 2 cups mini marshmallows and the crumb mixture. Bake 30 minutes or until topping is golden and marshmallows are melted.
Storage and Make-Ahead
- Store leftovers covered in the refrigerator for up to 4 days. Reheat in the oven until warmed through to preserve topping texture.
- This casserole can be assembled a day in advance, covered and stored in the fridge; bake just before serving for best results.
Notes and Tips
- Use fresh rosemary for the brightest flavor; you may omit rosemary if you prefer a purely sweet version.
- Substitute milk or heavy cream for the half-and-half to adjust richness.
- If you prefer no marshmallows, the crumb topping alone creates a lovely savory-sweet crunch.
- Watch closely if using the broiler to brown marshmallows—only a minute or two is usually needed.
Recipe by: Amy Duska. Sweet potato casserole with rosemary makes a sweet and savory twist on this classic holiday side dish.
Originally posted in November 2014 and updated in November 2019 with clarified instructions.