Sweet Potato Casserole Recipe With Streusel and Marshmallows: Triple-Layered Crunch and Gooey Bliss

This sweet potato casserole recipe delivers the perfect harmony of creamy, spiced sweet potatoes, buttery streusel topping, and golden-brown marshmallows—a triple-layered masterpiece that becomes the star of any holiday table. 🌟 The secret lies in baking the sweet potatoes until tender yet firm, then topping them with a crumbly streusel that adds texture and a caramelized edge.

What sets this version apart is the marshmallow layer, broiled to perfection for that classic toasted crunch while staying gooey inside.

The recipe is designed for foolproof success, even for beginners. You'll start with a simple sweet potato mixture—sweetened just enough to balance the spices—then layer on the streusel and marshmallows for that iconic presentation.

The baking process is straightforward: first in the oven to set the base, then under the broiler to achieve that signature golden-brown finish on the marshmallows. No special equipment is needed, just a few key ingredients and patience for the best results.

What you'll end up with is a restaurant-quality side dish that's creamy, crunchy, and sweet all at once. The sweet potatoes stay moist and flavorful, the streusel adds a buttery crunch, and the marshmallows deliver that irresistible caramelized topping.

This casserole is perfect for holiday gatherings, family dinners, or even a cozy weeknight meal when you crave comfort food.

Ready in about 45 minutes, this recipe scales easily to feed a crowd or serves as a satisfying single portion. The best part? Leftovers reheat beautifully, making it ideal for meal prep. Let's get started on creating this timeless classic!

Ingredients for sweet potato casserole recipe with streusel and marshmallows

Sweet potatoes, buttery streusel, and marshmallow magic—this triple-layered casserole delivers restaurant-quality comfort in one dish.

The sweet potatoes are where it all begins. Organic sweet potatoes from Whole Foods or your local farmers market stay creamier than store-bought, but any firm, vibrant orange ones work. Peeled and cubed evenly (about 1-inch pieces), they cook faster and absorb flavors better. Costco often has them pre-peeled in the fall, which saves time. For the streusel, cold butter is non-negotiable—it creates those perfect flaky layers. Plugrá brand butter has the highest fat content, but any unsalted butter works if you adjust the salt separately. The walnuts? Only add them if you love texture—they're optional but add a lovely crunch that contrasts beautifully with the marshmallows.

No evaporated milk? Heavy cream or whole milk works in a pinch, though the texture will be slightly lighter. Short on vanilla? Vanilla bean paste gives deeper flavor, or a splash of bourbon adds warmth. The cinnamon and nutmeg should be freshly ground if possible—Penzeys sells pre-ground blends that stay potent for months. For the marshmallows, Kraft or Jet-Puffed mini marshmallows are the gold standard, but any brand in uniform size works. Pro tip: Toast the walnuts (if using) in a dry pan for 3 minutes before mixing into the streusel—they'll taste fresher and add more crunch. The streusel should look like wet sand when mixed, not dry crumbs.

This casserole reheats beautifully—just cover with foil and warm at 350°F for 20 minutes. The marshmallow layer stays gooey when reheated properly, but if it gets too firm, a quick broil for 1-2 minutes brings back that perfect texture. Store leftovers in an airtight container for up to 5 days, though I rarely have any. For make-ahead prep, assemble the casserole (without marshmallows) up to 24 hours ahead, then bake fresh. The flavors meld beautifully overnight, and the streusel stays crisp. Freeze unassembled layers separately for up to 3 months—just bake straight from frozen, adding 10-15 minutes to the cooking time.

Step-by-step instructions for sweet potato casserole with streusel and marshmallows

Here's how to create that perfect triple-layered dessert with crispy streusel, creamy filling, and gooey marshmallow topping.

Preheat your oven to 375°F while you prepare the sweet potatoes. In a large mixing bowl, combine the 2 lbs peeled and cubed large sweet potatoes, 0.5 cup granulated sugar, 1.5 cups evaporated milk, 2 whole large eggs, and 1 tsp vanilla extract. Mix until all ingredients are fully incorporated and the sweet potatoes are evenly coated.

This mixture should be thick but pourable—if it's too thick, add 1-2 tablespoons of evaporated milk to reach the right consistency. The sweet potatoes should be tender but not mushy, so if they feel firm, microwave them for 1-2 minutes to soften slightly. Taste and adjust sweetness if needed, remembering this will be balanced by the streusel and marshmallows.

In a separate bowl, create the streusel topping by combining the 1.5 cups all-purpose flour, 1 cup packed light brown sugar, 1.5 tbsp ground cinnamon, 0.5 tsp ground nutmeg, 0.5 tsp salt, and 0.5 cup chopped walnuts (if using). Cut in the 0.75 cup cold cubed unsalted butter using a pastry cutter or your fingers until the mixture resembles coarse crumbs with some pea-sized butter pieces remaining.

Here's the thing—don't overwork this mixture. You want it to stay crumbly so it creates that perfect crispy texture when baked. If it starts to look like wet sand, add 1-2 tablespoons more flour to bring it back. Sprinkle half of this streusel mixture evenly over the sweet potato filling in a greased 9x13-inch baking dish.

Spread the sweet potato mixture evenly over the streusel in the baking dish, pressing down gently to create a smooth surface. This layering is crucial—it ensures even baking and that perfect balance of textures. Sprinkle the remaining streusel mixture evenly over the top of the sweet potato layer.

Bake in the preheated 375°F oven for 40-45 minutes until the edges are golden brown and the filling is set but still slightly jiggly in the center. Here's where it gets tricky: you want it to be just set but not completely firm, as it will continue cooking with the marshmallows. The streusel should be crispy and golden—if it's browning too quickly, tent with foil after 30 minutes.

Remove the casserole from the oven and immediately sprinkle the 4 cups mini marshmallows evenly over the entire surface. Return it to the oven and bake for an additional 10-15 minutes until the marshmallows are golden brown and slightly puffed. Watch carefully—they go from perfect to burnt quickly!

This is the moment that matters: you'll know it's done when the marshmallows have that beautiful toasted color and the casserole has a caramelized sheen on top. The filling should be set but still slightly warm in the center. If the marshmallows aren't browning enough, broil for 1-2 minutes on high, keeping a close eye to prevent burning.

Let the casserole rest for 10 minutes before serving—this allows the layers to set properly and the juices to redistribute. The streusel will be crispy, the sweet potato filling will be creamy, and the marshmallows will be gooey and caramelized on top. Serve warm with a scoop of vanilla ice cream or a dollop of whipped cream for the ultimate dessert experience.

Here's the secret to serving success: cut through the streusel layer gently with a knife to create clean slices. The contrast of textures—crispy streusel, creamy sweet potato, and gooey marshmallows—is what makes this casserole so irresistible. Store leftovers in the refrigerator for up to 3 days and reheat in the oven at 350°F for 10-15 minutes to restore that perfect texture.

Serving suggestions for this dish

Classic Dessert Pairings

Serve your sweet potato casserole warm with a scoop of vanilla bean ice cream—the cool creaminess balances the warm, caramelized marshmallows beautifully. I love using Ben & Jerry's Phish Food or Häagen-Dazs Vanilla for that rich, creamy contrast.

For a lighter option, try whipped cream with a sprinkle of ground cinnamon to echo the casserole's flavors. 🥛

Beverage Pairings

A hot cup of chai tea or spiced apple cider complements the warm spices in the casserole perfectly. For coffee lovers, a dark roast with a hint of cinnamon enhances the dish's cozy flavors. If you prefer something lighter, a glass of cold milk or sparkling cider works wonderfully. 🍵

Presentation Tips

Use a 9x13-inch baking dish for even baking, but transfer to a wooden serving board or slate platter before serving to elevate the presentation. Garnish with toasted pecans or candied walnuts for extra crunch. For a festive touch, sprinkle with powdered sugar or crushed peppermint during the holidays. 🍂

Family-Style Serving

This casserole is perfect for holiday gatherings or weeknight family dinners. Serve it in the center of the table with spoons for scooping to encourage sharing. Pair with buttery dinner rolls or crusty bread to soak up any extra sweet potato filling.

For a fun twist, let kids assemble their own mini portions with individual scoops of ice cream. 👨‍👩‍👧‍👦

Make-Ahead Serving

Assemble the casserole (without marshmallows) up to 24 hours ahead and refrigerate. Bake fresh before serving for the best texture. For meal prep, store leftovers in an airtight container for up to 5 days.

Reheat in the oven at 350°F for 15 minutes to restore that gooey marshmallow perfection. 📅

Garnish Variations

Add a drizzle of caramel sauce or honey for extra sweetness. For a savory contrast, sprinkle with flaky sea salt right before serving. A pinch of smoked paprika adds depth, while toasted coconut flakes bring a tropical twist.

Keep it simple or get creative—it’s all about balancing textures and flavors! 🌟

Frequently asked questions