The original recipe is made with Idaho potatoes. Are they special? Do they taste different? Creamier? Never seen one, or tasted one; not a clue.
What I do know is that different potatoes make it more or less fudgier. I guess the starch content is different. Or something like that. 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.
Easy steps for making this cake:
- Shred unbaked potato.
- Put all ingredients in the processor, including potato. Mix well.
- Scrape chocolate batter into prepared pan and bake.
- Make the one-bowl peanut butter chocolate frosting.
- Frost top of cooled cake.
- Eat cake with frosting.
About the potato in this recipe.
Since the potato is the guest here, we should talk a bit about it.
The magic of this cake, in my opinion, is that the potato is used raw. Just grate it and mix it. No need to steam or boil it, make a puree, then wait for it to cool, bla, bla, bla.
I live in Buenos Aires and we don’t have access to many potato varieties. We have russet potatoes and a variety that has darker skin. Both are very common. This is to explain that any potato can be used. Even sweet potatoes.
I think that if you have access to a creamier potato the consistency would be fudgier. That said, the cake is amazing with any regular potato, and there’s no need to buy any fancy ones.
What about the peanut butter chocolate frosting?
Steps for making the frosting:
- Melt chocolate with some of the cream. I find it’s the easiest way to melt it in the microwave without risk of burning it. Even so, you have to be very careful and put the bowl in 10-second spurts and mix it well before popping it again. Sometimes the chocolate looks whole but it is mostly melted already in the center.
- Mix with the peanut butter (image above, left).
- Add powdered sugar and/or cream until you get the consistency you want (image above, right). It depends a lot on how thick the peanut butter and cream are. A lot. Sometimes you don’t need to add any sugar.
Frosting this chocolate potato cake.
Chocolate Potato Cake, Incredibly moist, sweet and fudgy, it’s mixed in the food processor! The chocolate peanut butter frosting is just, literally, the icing of this fabulous cake.
For the cake:
- 4-oz. (115g) Idaho russet potato (or another type), peeled and cut to fit feed tube
- 2 cups (450g) sour cream, at room t°
- 1 ¾ cups (230g) all-purpose or cake flour
- 1 ¾ cups sugar
- ¾ cup unsweetened cocoa powder
- ½ cup (115g) unsalted butter, room tº
- 2 large eggs, room t°
- 1 ½ teaspoons baking soda
- 1 teaspoon vanilla extract
- ½ teaspoon salt
For the peanut butter frosting:
- 1 cup (250g) peanut butter, at room t°
- 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.
Tips & tricks for this recipe:
- Potato: I had different levels of fudginess depending on the potato I use. I guess it’s the amount of starch. They all work perfectly well, but you might find that you like the consistency more with one or another.
- 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 don’t need to add any 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.
- Freezing it: wrap it well and freeze it for up to a month, as any other chocolate cake. Defrost at room t°.
Keywords: potato cake, chocolate potato cake
from Bon Appétit – January 1989