This oven baked 4-ingredient sweet potato casserole is straight from my Aunt Linda’s Sunday supper table. She brought it over one weekend, set it on the counter in a glass baking dish with those perfectly toasted marshmallows and pecans on top, and it disappeared before the roast even hit the table. When she told us it was only four ingredients, we all made her repeat it twice. It’s the kind of cozy, no-fuss recipe that feels special enough for holidays but is easy enough for a busy weeknight when you still want something a little nostalgic and comforting.
Serve this sweet potato casserole warm, straight from the oven, with simple savory mains like roasted chicken, baked ham, or a pot roast to balance the sweetness. It’s also great alongside green beans, a crisp salad, or steamed broccoli to add some freshness to the plate. If you’re doing a holiday spread, it fits perfectly next to stuffing, gravy, and rolls. For leftovers, I like a small scoop reheated the next morning with a fried egg on the side for a cozy, slightly indulgent breakfast.
Oven Baked 4-Ingredient Sweet Potato CasseroleServings: 8
Ingredients
3 pounds sweet potatoes, peeled and cut into 1-inch chunks
4 tablespoons unsalted butter, melted
1/3 cup packed light brown sugar
2 cups mini marshmallows, divided
1/2 cup chopped pecans (optional garnish, not counted in the 4 core ingredients)
Nonstick cooking spray, for the baking dish
Pinch of salt (optional, to taste)
Directions
Preheat your oven to 375°F (190°C). Lightly coat a 9x13-inch glass baking dish with nonstick cooking spray so the sweet potatoes don’t stick.
Place the peeled, chopped sweet potatoes in a large pot and cover them with cold water by about 1 inch. Add a pinch of salt if you like. Bring to a boil over high heat, then reduce to a simmer and cook for 12–15 minutes, or until the sweet potatoes are very tender when pierced with a fork.
Drain the sweet potatoes well and return them to the warm pot. Let them sit for 1–2 minutes so excess moisture can steam off; this helps keep the casserole from getting watery.
Add the melted butter and brown sugar to the pot with the hot sweet potatoes. Mash everything together with a potato masher until mostly smooth, leaving a few small chunks if you like a bit of texture. Taste and adjust sweetness or salt if desired.
Spread the mashed sweet potato mixture evenly into the prepared glass baking dish, smoothing the top with a spatula so it bakes and browns evenly.
Sprinkle 1 cup of the mini marshmallows evenly over the top of the sweet potatoes. If using, scatter the chopped pecans over the marshmallows for a toasty crunch.
Place the casserole in the preheated oven and bake for 15 minutes, until the sweet potatoes are heated through and the marshmallows are starting to puff and melt.
Carefully remove the dish from the oven, sprinkle the remaining 1 cup of mini marshmallows evenly over the top, and return it to the oven for another 5–8 minutes, or until the marshmallows are golden brown and toasted on top. Watch closely toward the end so they don’t burn.
Let the casserole rest for about 5–10 minutes before serving. This helps it set up slightly and makes it easier to scoop while still giving you that gooey, toasty marshmallow topping in every serving.
Variations & Tips
To keep this true to the “only 4 ingredients” promise, the core ingredients are sweet potatoes, butter, brown sugar, and mini marshmallows; the pecans are an optional garnish if you want that classic crunchy look from the photo. If you prefer a less sweet version, cut the brown sugar down to 1/4 cup or skip the second layer of marshmallows and just use 1 cup on top. For a make-ahead option, you can mash the sweet potatoes with butter and brown sugar, spread them in the dish, cover, and refrigerate up to 24 hours. When you’re ready to bake, bring the dish closer to room temp while the oven preheats, then add the marshmallows and bake until hot and toasted (you may need a few extra minutes). If you want a nut-free version, simply leave off the pecans; you’ll still get a pretty, golden marshmallow topping. For a slightly fancier twist that doesn’t add to the ingredient list, brown the butter before mixing it in with the sweet potatoes to add a deeper, nutty flavor. And if you’re cooking for a very small household, halve the recipe and bake it in an 8x8-inch glass dish, checking a few minutes early so the marshmallows don’t overbrown.
