Polenta Plum Upside Down Cake is a delicious, Italian-themed confection suitable for both dessert and breakfast. The cake gets some character and texture from the addition of cornmeal, and is beautifully perfumed with orange zest, cardamom and vanilla. The caramelized plum topping is the icing on the cake.
With such a large variety of plums and pluots available at the market these days, it was tough to decide which way to go. These prune plums called out to me (or they were the loudest anyway), most likely because we don’t cross paths very often. Turned out to be a good decision. I really love the appearance of these thin slices of plums on the top of the cake. They’re also quite delicious, but any red or black plum would do in this recipe.
Method wise, this is very much a traditional upside down cake. First, you caramelize some sugar. Then whisk in the butter, and pour it onto the bottom of your prepared pan. Next, comes the plums. I simply lined the bottom of the pan with overlapping plum slices, starting from the outside and working my way in. Then it’s time to mix the batter. Pour that on top, smooth it out and bake away. A springform pan makes unmolding this cake, well a piece of cake. Plus, I experienced zero leakage, so springform is definitely what I would recommend.
The cake batter itself diverges from the traditional version quite a bit. I went cornmeal cake. Or polenta if you’re trying to sound sophisticated. And this is not any old cornmeal cake here. I adapted the basic recipe from a very talented chef, Mr. David Lebovitz. You have likely heard of him. I’ll add the link below in the recipe section, but what I’m trying to get at is this cake is not only a mix of cornmeal and AP flour, but it’s also a mix of butter and extra virgin olive oil. I’ve definitely mixed butter and oil in recipes before. In those cases, I used a neutral oil such as vegetable or canola oil. The theory is the butter provides the superior flavor and the oil adds additional moisture that just doesn’t happen with straight up butter. Oil might also create a more tender texture. Oil tends to coat the proteins in flour better than butter does (maybe because butter is 20% water or because it starts off solid?), and helps prevent the proteins from binding with water to create gluten. Gluten = Chewy. On the other hand, butter tends to create a lighter cake. When butter is creamed with sugar, air pockets form. When the water in butter evaporates, steam is released which is another reason a butter cake might be more airy. Now, David doesn’t use the typical vegetable oil in this cake. I’ve used extra virgin olive oil as a stand alone fat in cakes for that pronounced fruity flavor, but when I saw a butter-evoo combo, I was really intrigued. We have a double flavor punch, the moisture benefits from oil and airiness from the butter. Awesome.
Now, what could make this cake even tastier? My first thought was orange zest. There’s a delicious olive oil cake I used to make that was chock full of orange zest. I didn’t want to overdo it here, but I added just enough to make the citrus apparent. Next was cardamom. I love the way orange and cardamom play off each other, whether it’s in a savory or sweet application. I also think cardamom and plums go together well. Oh yeah. I based another dessert off of this combination. My Cardamom Honey Ice Cream with Roasted Plums. Am I starting to become predictable? I honestly completely forgot about that post until this very moment. Anyway, the last flavor addition was a little vanilla extract because why not. This Polenta Plum Upside Down Cake has flavor and texture, and is certainly a looker. If anything, I hope this post gives you some cakespiration.
- 10 (13oz) prune plums or plums of choice, sliced in ½ inch wedges
- ¾ cup granulated sugar
- ⅓ cup water
- 2 tbsp unsalted butter, softened at room temperature
- ¾ cup + 2 tbsp all-purpose flour
- ½ cup + 2 tbsp finely ground yellow cornmeal
- 1 ½ tsp baking powder
- 1 tsp kosher salt
- ¼ tsp ground cardamom
- 1 cup granulated sugar
- 1 stick unsalted butter, softened at room temperature
- 4 large eggs, at room temperature
- 1 egg yolk
- ½ tsp finely grated orange zest
- ½ tsp vanilla extract
- ¼ cup plus 2 tbsp extra virgin olive oil
- Prepare pan and oven: Butter a 9-inch springform pan and line with parchment, allowing to go up slightly on the edges to prevent leaking. Butter over the parchment. Place on a parchment line baking sheet. Preheat oven to 350°F.
- Caramelize the sugar: Add sugar to a medium sized pot. Carefully pour over water so the sugar is just submerged. Make sure the sides of the pot are clean. Turn heat to medium and bring mixture to a simmer. Allow to simmer until all the water has evaporated and the sugar begins to caramelize. Do not stir during this process. As sugar begins to take on color, you can gently swirl the pan to encourage even browning. Once the sugar reaches an amber color, like maple syrup, remove the pan from the heat and whisk in the butter. Pour immediately into prepared pan.
- Fan out plums: Working from the outside of the pan in, place down plum wedges slightly overlapping, in a circular pattern. The bottom of the pan should be completely covered by plums.
- Mix dry ingredients: In a bowl, sift together all dry ingredients (AP flour through cardamom).
- Cream and beat wet ingredients: In the bowl of a standing mixer, add sugar and butter. Using the paddle attachment, beat together over medium speed for about 3 minutes or until light and fluffy. Beat in eggs, one at a time, until fully incorporated. Stir in zest and vanilla. While mixing over low speed, gradually stream in oil until emulsified.
- Mix wet and dry: Add dry ingredients to wet ingredients in 3 portions, stirring after each addition. Do not over mix.
- Bake and serve: Pour batter in pan over plums. Smooth out top. Baking on baking sheet on the center rack of the oven for 50-60 minutes or until golden brown and a toothpick inserted into the center comes out clean. Cool on rack for about 1 hour. Run a knife along the sides of the pan, and carefully remove outer ring. Invert onto cooling rack and remove base of pan and parchment. Cool completely before serving. Enjoy.