Delectable swirls of sweet potato, chocolate, and warm pumpkin pie spice come together in this moist, tender loaf cake. The batter produces a light crumb balanced by rich chocolate and subtly spiced sweet potato layers, while a simple confectioners’ sugar glaze adds the perfect finishing sweetness. This loaf captures the essence of autumn baking and makes a comforting dessert or an indulgent morning treat with coffee.
Use baked, mashed sweet potato for the best texture and natural sweetness. The recipe is forgiving: you can prepare the sweet potato ahead of time and keep it refrigerated until you assemble the batter. The marbling technique creates an attractive interior and ensures each slice offers a variety of flavors in every bite.
Marbled Sweet Potato-Chocolate Loaf Cake
Ingredients
- ⅔ cup (150 grams) unsalted butter, softened
- 1 cup (200 grams) granulated sugar
- 2 large eggs (100 grams), room temperature
- ¾ cup (182 grams) mashed baked sweet potato
- 1½ teaspoons (6 grams) vanilla extract, divided
- 1¾ cups (219 grams) all-purpose flour
- 1½ teaspoons (7.5 grams) baking powder
- 1½ teaspoons (4.5 grams) kosher salt
- 1 ounce (28 grams) bittersweet chocolate, melted and cooled slightly
- 1 teaspoon (2 grams) ground cinnamon
- ½ teaspoon (1 gram) pumpkin pie spice
- 1 cup (120 grams) confectioners’ sugar
- 1½ to 2 tablespoons (22.5 to 30 grams) whole milk, divided
Instructions
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Preheat the oven to 350°F (180°C). Prepare an 8½ x 4½-inch loaf pan by spraying it with baking spray that contains flour, or grease and flour the pan. Line the pan with parchment paper with the edges extending over the sides to make removing the loaf easy.
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In the bowl of a stand mixer fitted with the paddle attachment, beat the softened butter and granulated sugar on medium speed until light and fluffy, about 3 to 4 minutes, scraping the bowl as needed. Add the eggs one at a time, mixing until each is fully incorporated. Beat in the mashed sweet potato and 1 teaspoon of the vanilla extract.
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In a medium bowl, whisk together the all-purpose flour, baking powder, and kosher salt. With the mixer on low speed, add the dry ingredients gradually to the butter-sweet potato mixture, mixing until just combined and stopping to scrape the bottom and sides of the bowl to ensure an even batter.
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Portion about 1 cup (roughly 280 grams) of batter into each of two separate bowls. Stir the melted and slightly cooled bittersweet chocolate into one bowl until evenly combined. Stir the ground cinnamon and pumpkin pie spice into the second bowl. Leave the remaining batter unflavored in its original bowl for the plain sweet potato layer.
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Using a 1½-tablespoon spring-loaded scoop or a tablespoon, drop spoonfuls of each batter into the prepared pan in an alternating pattern, creating a single layer. Firmly tap the pan a few times on the counter lined with a kitchen towel to level the batter. Continue scooping and tapping until all the batter is used. To create a marbled effect, gently swirl the batters with a butter knife or offset spatula—do not overmix or the marbling will disappear.
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Bake until a wooden skewer inserted in the center comes out clean and an instant-read thermometer registers at least 205°F (96°C), about 55 minutes to 1 hour. Allow the loaf to cool in the pan for 10 minutes, then lift it out using the parchment overhang and transfer to a wire rack to cool completely.
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For the glaze, whisk the confectioners’ sugar with 1½ tablespoons (22.5 grams) of milk and the remaining ½ teaspoon (2 grams) vanilla in a small bowl until smooth. If the glaze is too thick to spread, whisk in the remaining ½ teaspoon (7.5 grams) milk a little at a time until you reach a spreadable consistency. Spoon or drizzle the glaze over the cooled loaf. Store the cake in an airtight container in the refrigerator for up to 3 days.
Tips & Notes
Sweet potato preparation: Roast or bake whole sweet potatoes until tender, scoop out the flesh, and mash until smooth. Drain excess moisture if needed so the batter isn’t watery. Using canned sweet potato puree is acceptable in a pinch—adjust moisture if it seems loose.
Chocolate: Choose a good-quality bittersweet chocolate for a deeper cocoa flavor. Melt gently over a double boiler or carefully in short bursts in the microwave, stirring between intervals to avoid seizing.
Marbling: Alternate spoonfuls of each batter and swirl just enough to make pretty patterns. Over-swiring blends the flavors and colors, so a light hand yields the best presentation and texture.
Make-ahead: Bake the loaf a day ahead and keep it wrapped at room temperature, or refrigerate and remove 30 minutes before serving to bring back tenderness. Glaze just before serving for the best appearance.
Serving suggestions: Serve slices plain, with a dollop of whipped cream, a scoop of vanilla ice cream, or alongside a warm cup of coffee or tea.
Variations: Swap the pumpkin pie spice for a simple mix of cinnamon and nutmeg, or add a handful of chopped toasted pecans into the batter for extra texture. For a more chocolate-forward loaf, stir finely chopped chocolate or chips into the chocolate batter.
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