This is a unique cake, incredibly moist, sweet and fudgy, it's mixed in the food processor! The chocolate peanut butter frosting is just, literally, the icing on this fabulous cake.
For the cake:
- 4-oz. (115g) russet potato (or another type), raw, peeled and cut to fit feed tube
- 2 cups (450g) sour cream, at room temperature
- 1 ¾ cups (230g) all-purpose or cake flour
- 1 ¾ cups sugar
- ¾ cup unsweetened cocoa powder
- ½ cup (115g) unsalted butter, room temperature
- 2 large eggs, room temperature
- 1 ½ teaspoons baking soda
- 1 teaspoon vanilla extract
- ½ teaspoon salt
For the peanut butter frosting:
- 1 cup (250g) peanut butter, at room temperature
- 2 oz (55g) semisweet chocolate, melted
- 3-4 tablespoons whipping cream
- ¼ to ½ cup powdered sugar, optional, see notes below
For the cake:
- Preheat oven to 350ºF /180°C.
- Butter and flour 9×13 inch (20x26cm) cake pan or line it with parchment paper.
- If you don’t have a large food processor you may need to make it in two batches.
- Put the shredding disc in the food processor and shred the potato.
- Change the shredder for the steel knife. If you had to remove the shredded potato momentarily put it back in the bowl of the processor.
- Add the remaining ingredients and process for 3-4 minutes, stopping to scrape sides of bowl and making sure nothing sticks to the bottom.
- If you have to make it in batchen transfer each mixture to a large bowl and then mix it all together.
- Transfer chocolate mixture to prepared pan.
- Bake for 35 to 40 minutes, until tester inserted in center comes out clean.
- Cool completely in pan and invert onto platter.
- Frost with peanut butter chocolate frosting or dust with powdered sugar.
For peanut butter frosting:
- Melt chocolate and 2 tablespoons of cream in microwave or double boiler.
- Mix thoroughly with peanut butter and rest of the cream.
- If you want a thicker consistency add some powdered sugar, a few tablespoons at a time. If it's too thick for your taste add a few tablespoons more cream.
- Spread on top of the cooled cake with a spatula.
Potato: I use Russet, which for me are the regular, everyday ones. The original recipe is made with Idaho potatoes, and I read that they are similar in starch content, which is what makes the difference because it can make the cake more or less fudgier. So make it with your favorite and see how it goes. It will be amazing with any type of potato, but you might see subtle differences.
Frosting: after mixing peanut butter with chocolate, add powdered sugar and/or cream until you get the consistency you want. It depends a lot on how thick the peanut butter and cream are. A lot. Sometimes you hardly need to add sugar at all.
Powdered sugar: you can only use a dusting of powdered sugar instead of making the frosting. It is a wonderful plain cake.
Pans: it can be made in any pan you want - cupcakes, round layers, square, even loaf pan. I like to make it in a square pan (image above) because I like to cut cakes in squares. It's sort of a sheet cake.
Make ahead: the chocolate cake can be baked in advance and kept in the refrigerator for 3-4 days, or in the freezer for a month, always well wrapped. Defrost at room temperature. Same with the frosting, it keeps well for 1-2 weeks in the refrigerator, covered.
- Serving Size: 1/12
- Calories: 514
- Sugar: 34.6 g
- Sodium: 388.8 mg
- Fat: 28.5 g
- Carbohydrates: 58.6 g
- Protein: 12.2 g
- Cholesterol: 69 mg
Keywords: potato cake, chocolate potato cake