Ingredients
- 3/4 cup (90 g) graham cracker crumbs (about 5 full sheets)
- 1/8 cup (25 g) white granulated sugar
- 1/4 cup (60 g) salted butter, melted
- 1 lb (450 g) sweet potatoes (2 to 3 roots)
- 1 can (14 oz / 400 g) sweetened condensed milk
- 1/4 cup (30 g) salted butter, softened
- 2 eggs
- 1 teaspoon grated orange zest (optional)
- 1 teaspoon ground cinnamon
- 1/2 teaspoon ground ginger
- 1/4 teaspoon ground cloves
- 2 cups (100 g) mini marshmallows
Similar sweet potato pie bar recipes use almost the same lineup: graham cracker crumbs, sugar, melted butter for the crust, then mashed sweet potatoes, sweetened condensed milk, eggs, butter, and warm spices for the filling, plus mini marshmallows on top. The optional orange zest is a twist some bakers add to brighten the filling and complement the sweet potato and spice.
Step‑by‑Step Instructions
Start by cooking the sweet potatoes so they’re ready to mash. Place the sweet potatoes in a large stockpot, cover with water, and bring to a boil; cook until they’re fork‑tender, about 15–18 minutes, then drain and let them cool enough to handle. Many bar and pie recipes call for either boiling or roasting sweet potatoes; extensive sweet potato pie testing suggests roasting gives deeper flavor and less moisture, but boiling is a quicker method that still yields a smooth filling when handled properly. Once cooled, peel the sweet potatoes and mash them until smooth; a potato masher, fork, or mixer will all work, similar to instructions in sweet potato pie bar recipes that don’t require a food processor.
Preheat your oven to 350°F (180°C). Line an 8‑inch square baking pan with parchment paper, leaving an overhang on two sides so you can lift the bars out easily after chilling; this parchment “sling” is a standard tip in bar recipes for clean removal and slicing.
To make the crust, combine the graham cracker crumbs, granulated sugar, and melted butter in a bowl, stirring until the crumbs are evenly coated and resemble wet sand. Press this mixture firmly into the bottom of the prepared pan to form an even layer; graham cracker crust instructions consistently emphasize pressing firmly so the crust holds together in slices. Bake the crust for about 15 minutes, until lightly fragrant and just starting to set, a step that matches other sweet potato pie and bar recipes using blind‑baked graham bases.
While the crust bakes and cools, prepare the filling. In a mixing bowl, add the cooled mashed sweet potatoes, sweetened condensed milk, softened butter, eggs, cinnamon, ginger, cloves, and orange zest if using. Beat the mixture with an electric mixer until completely smooth and well blended, scraping down the bowl as needed; sweet potato pie bar recipes typically aim for a silky, lump‑free custard filling by thoroughly mixing at this stage.
Pour the sweet potato filling over the baked graham cracker crust and smooth the top with a spatula. Return the pan to the 350°F oven and bake for 35–45 minutes, or until a skewer or toothpick inserted into the center comes out clean or with just a few moist crumbs but no wet batter, the same doneness cue used in comparable sweet potato pie bar recipes. The edges will look set, and the center should no longer jiggle like liquid.
Let the bars cool to room temperature in the pan, then refrigerate for 4–5 hours until fully firm; several sources on sweet potato pie bars and custard desserts emphasize this chill time so the filling sets enough to slice cleanly and the flavors have time to develop. For a deeper flavor, you can also roast the sweet potatoes instead of boiling them next time—sweet potato pie experts have found that roasting at higher temperatures caramelizes more natural sugars and evaporates some moisture, resulting in a richer, more flavorful filling.
Once the bars are chilled and firm, preheat your broiler. Sprinkle the mini marshmallows evenly over the top of the sweet potato layer. Place the pan under the broiler for 2–3 minutes, watching very closely, until the marshmallows are puffed and toasted golden brown in spots; marshmallow‑topped bar recipes warn that broilers can go from perfectly toasted to burnt in seconds, so it’s important not to step away. Remove the pan from the oven and let the topping cool briefly so the marshmallows set enough to cut.
Use the parchment overhang to lift the bars out of the pan and transfer to a cutting board. Cut into squares with a serrated knife, wiping the blade between cuts for clean edges, a standard tip in bar recipes, especially when a sticky topping like marshmallow is involved. Serve the bars chilled or slightly warmed, as similar sweet potato pie bar recipes note that both temperatures work well depending on preference.