Sweet potato dump cake is the kind of dessert you pull together when you want something warm, cozy, and generous without juggling a dozen steps. It eats like a cross between sweet-potato pie and a crumbly cobbler. You’ll make a simple spiced sweet-potato base, cover it with dry cake mix, dot the top with butter, and bake until the surface turns deeply golden and the edges bubble. The payoff is big: a creamy, custardy layer crowned with a crisp, buttery crust.
It’s flexible, too. You can use roasted sweet potatoes for deeper flavor, or canned yams for speed. A yellow cake mix keeps the topping light and buttery; a spice cake mix leans harder into fall flavors. Pecans are optional, but they add welcome crunch. Serve it warm with softly whipped cream or vanilla ice cream and you’ve got an easy finish to a weeknight dinner, a Friendsgiving, or the “please bring a dessert” invite that arrived an hour ago.
The method is forgiving, but a few details matter. Balancing sugars keeps the filling plush without tipping into cloying. Evaporated milk gives body and sets into a spoonable custard; eggs help it slice neatly. A small pinch of salt brightens the sweet potatoes. And the butter on top needs to cover most of the surface so the dry mix hydrates and turns crisp instead of floury. If a corner looks dry at the 30-minute mark, just spoon a little melted butter over that area and keep baking.
This is not a precious dessert; it’s a practical one. The batter goes straight into a 9×13 pan, and the oven does the rest. The leftovers hold well in the fridge, and the whole pan reheats nicely for a second night. If you want make-ahead insurance, roast the sweet potatoes a day early or mix the filling and chill it. When it’s time to bake, you’ll only need to add the dry mix and butter. Easy going, dependable, and right at home on a fall table.
The Best Pan, Temperature, and Texture Cues
- Pan: A metal 9×13 pan browns most evenly, but glass works fine. If using glass, the top may brown a touch slower; check the center for set.
- Oven temp: 350°F (175°C) is the sweet spot—hot enough to brown the topping while the custard sets gently.
- Doneness signs: The top should be well-browned with buttery, crisp patches; the filling should bubble at the edges and no longer look soupy in the center. A slight jiggle is normal; it will firm as it cools.
Ingredients and Substitutions That Work
- Sweet potatoes: Roasted flesh gives the best flavor. Canned yams (drained) work when time is tight. You’re aiming for about 4 packed cups (about 800–900 g) of mash.
- Milk: Evaporated milk sets into a smooth custard. Whole milk or half-and-half can fill in if needed.
- Cake mix: Yellow is classic; spice cake adds extra warmth. Both bake up similarly.
- Butter: Slicing cold butter into thin pieces gives even coverage. Melted butter can be drizzled, but be thorough.
- Spices: Pumpkin-pie spice keeps things simple. Add a little extra cinnamon if you like a warmer profile.
- Nuts: Pecans bring texture. Skip them if you need a nut-free version.
Recipe: Sweet Potato Dump Cake (9×13 Pan)
Yield, Time & Equipment
- Servings: 12 squares
- Active prep: 20 minutes (10 minutes if using canned yams)
- Bake time: 50–65 minutes
- Total time with roasted sweet potatoes: 1 hour 45 minutes–2 hours
- Total time with canned yams: 1 hour–1 hour 15 minutes
Equipment
- 9×13-inch (23×33 cm) baking pan
- Large mixing bowl and whisk (or hand mixer)
- Rubber spatula
- Measuring cups and spoons
- Knife or bench scraper to slice butter
- Foil (optional, for tenting if top browns too fast)
Ingredients
For the sweet-potato base
- Roasted sweet-potato flesh, mashed — 4 cups (about 800–900 g), from 3 large sweet potatoes (about 2½ lb / 1.1 kg)
or canned yams, well drained — 2 cans (15 oz / 425 g each), about 3–3½ cups (600–700 g) - Evaporated milk — 12 fl oz (354 ml)
- Large eggs — 2
- Unsalted butter, melted — 4 Tbsp (½ stick / 56 g)
- Light brown sugar — ½ cup (100 g)
- Granulated sugar — ½ cup (100 g)
- Vanilla extract — 2 tsp (10 ml)
- Pumpkin-pie spice — 2 tsp (6 g)
- Ground cinnamon — 1 tsp (3 g)
- Fine salt — ½ tsp (3 g)
For the topping
- Yellow or spice cake mix — 1 box (15.25 oz / 432 g)
- Unsalted butter, cold and sliced thin — 12 Tbsp (1½ sticks / 170 g)
- Chopped pecans (optional) — 1 cup (120 g)
Preparation
Step 1: Roast (if using fresh sweet potatoes)
- Preheat oven to 400°F (205°C). Pierce whole sweet potatoes several times.
- Place on a lined sheet and roast 45–60 minutes, until very tender. Cool until you can handle, then peel and mash until mostly smooth. Measure out 4 packed cups (800–900 g).
Shortcut: Skip roasting and use well-drained canned yams. Mash lightly; you’re aiming for mostly smooth with a few tiny bits.
Step 2: Mix the base
- Lower oven to 350°F (175°C). Grease the 9×13 (23×33 cm) pan.
- In a large bowl, whisk together mashed sweet potatoes, evaporated milk, eggs, melted butter, brown sugar, granulated sugar, vanilla, pumpkin-pie spice, cinnamon, and salt until smooth.
- Scrape the mixture into the prepared pan and smooth the surface.
Step 3: Add the topping
- Sprinkle the dry cake mix evenly over the sweet-potato base. Don’t stir.
- Distribute the cold butter slices across the entire surface, overlapping slightly so most dry mix is covered.
- Sprinkle pecans over the top, if using.
Note: If you prefer using melted butter, drizzle it slowly and evenly over the dry mix, pausing to let it soak in. The goal is moistening nearly all the powder.
Step 4: Bake
- Bake at 350°F (175°C) for 50–65 minutes.
- At 30 minutes, check coverage. If you see dry floury spots, spoon on a tablespoon or two of melted butter.
- The cake is done when the top is well-browned and crisp and the filling is bubbling at the edges with just a slight center jiggle.
Step 5: Cool and serve
- Let the pan rest 15–20 minutes so the custard can set. Serve warm.
- Add whipped cream or a small scoop of ice cream if you like.
Make-Ahead, Storage, and Reheating
- Make-ahead: Mix the sweet-potato base up to 24 hours in advance; cover and refrigerate. Add cake mix and butter just before baking.
- Room temp (short hold): Cool, then cover loosely and keep up to 6 hours the day you bake.
- Refrigerator: Cover tightly and chill up to 4 days.
- Freezer: Wrap portions well and freeze up to 3 months. Thaw in the fridge overnight.
- Reheat: Warm slices at 300°F (150°C) for 10–15 minutes, or microwave in short bursts until heated through.
Variations You Can Trust
- Maple-pecan: Swap ¼ cup (60 ml) of the evaporated milk for pure maple syrup and use pecans on top.
- Marshmallow finish: Scatter 1½ cups (75 g) mini marshmallows over the surface during the last 8–10 minutes of baking.
- Brown-butter boost: Brown the melted butter for the base until it smells nutty; cool slightly before whisking in.
- No-nut version: Omit nuts entirely or use pumpkin seeds for crunch.
- Spice-forward: Use a spice cake mix and add a pinch of ground ginger and nutmeg to the base.
Troubleshooting
- Dry patches of topping: You need more butter coverage. Spoon a little melted butter over dry spots at the halfway point and bake on.
- Soggy center after time is up: Bake longer. Ovens vary. Tent the top loosely with foil if it’s browning too fast and give it another 8–12 minutes.
- Overly sweet: Reduce granulated sugar in the base to ¼ cup (50 g) next time, especially if using a spice cake mix.
- Not setting cleanly: Ensure you included both eggs and baked until the edges bubbled. Cooling time helps the custard firm.
Ingredient Notes for Accuracy
- Sweet-potato quantity matters. If you have less than 4 cups (800–900 g) of mash, the filling will be thin and the topping can sink. If you have more, reserve the extra or the bake time may lengthen.
- Butter coverage equals crisp topping. Sliced cold butter is the most foolproof method to hydrate the dry mix evenly.
- Salt is not optional. A small amount sharpens flavor and keeps the sweetness in check.
Serving Suggestions
- Classic: Warm squares with whipped cream.
- Cold next-day treat: Chill overnight and serve cool; the custard firms and slices neatly.
- With coffee or tea: The buttery top holds its crunch even as the base stays tender, so it pairs well with a hot drink.
Nutrition (Estimated, per serving of 12; without nuts)
- Calories: ~430
- Total fat: ~19 g
- Saturated fat: ~11 g
- Carbohydrates: ~60 g
- Added sugars: ~35 g
- Fiber: ~3 g
- Protein: ~6 g
- Sodium: ~380 mg
With 1 cup (120 g) pecans, add roughly 80–90 calories and 8 g fat per serving.
These values are estimates based on standard databases and typical brand nutrition panels. Actual numbers vary with ingredient brands and exact portion size.
US–Metric Quick Reference
- 9×13-inch pan = 23×33 cm
- 1 box cake mix (15.25 oz) = 432 g
- 1½ sticks butter = 12 Tbsp = 170 g
- 4 cups mashed sweet potato = about 800–900 g
- 12 fl oz evaporated milk = 354 ml
Summary
This sweet potato dump cake keeps the work simple and the results generous. A well-spiced, custardy base meets a crisp, buttery crust, and you can scale the sweetness, swap the cake mix, or add nuts without fuss. Keep an eye on butter coverage and bake until the top is well-browned and the filling bubbles. The rest is easy: a warm pan of fall flavor, ready for the table.
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