Gooey, delicious, and gorgeous – the color of in-season plums is stunning! And this is peak plum season. Most plums are on the tart side which makes them perfect for caramelizing in butter and brown sugar. Sweet and tangy caramelized plums are topped with a moist and buttery almond cake. The cake is light and flavorful and perfectly spiced with cardamom and orange zest.
You can use any kind of plums you like. They should be ripe but not too ripe. Look for plums that are firm but have a slight “give” when lightly pressed. If the plums are soft, it will be hard to slice them and they’ll be too juicy for this recipe.
I made this summer cake with plums; you could also use another stone fruit like peaches or apricots. I made one test recipe with peaches. It was good, just not swoon-worthy. I have made the cake substituting ½ cup fine cornmeal or ½ cup coconut flour for ½ cup of the all-purpose flour. Both made delicious cakes (no need to make other adjustments to the recipe) and using coconut flour was an interesting variation.
The cake gets quite brown. So be sure to test for doneness as per the recipe instructions and properly prepare your pan so the cake does not stick. I grease the pan with shortening and then coat it with flour. I also use a round of parchment paper at the bottom of my pan to ensure that the cake turns out nicely. You can cut your own rounds or purchase pre-cut rounds. I love having these on hand to save time on busy (and lazy) days. I prefer to serve this cake as is and to let the plums be the star of the show.
Plum Upside-Down Cake
Ingredients
Caramel Plum Topping
- 1½ pounds plums
- 5 tablespoons butter
- ½ cup brown sugar
- 2 teaspoons heavy cream (optional)
Cake Batter
- 1 cup all-purpose flour
- ¾ cup extra-fine almond flour
- 1½ teaspoons baking powder
- ¼ teaspoon baking soda
- ¼ teaspoon salt
- 1 teaspoon cardamom
- 10 tablespoons unsalted butter, room temperature
- 1 cup sugar
- 2 teaspoons almond extract
- 1-2 teaspoons orange zest (I like just a hint of orange, adjust to your taste)
- 3 large eggs, room temperature
- ½ cup sour cream
Instructions
- Grease and flour a 10” cake pan and line the bottom with parchment paper. Do not use a spring form pan – the caramel topping will leak out. An oven-proof skillet will also work but it is a little more difficult to flip the cake due to the handle. A 9” cake pan that is at least two inches deep is also ok but will take a little longer to bake.
- Pre-heat the oven to 325° convection.
Caramel Plum Topping
- Wash the plums. Cut in half, remove the pits, and cut each half into 4.
- Melt the butter and brown sugar together. I use the microwave. Stir vigorously to combine. If mixture seems curdled, add the cream, heat for another 30 seconds, and stir together.
- Pour into the prepared cake pan. Spread the mixture evenly in the pan. Arrange the plum slices over the bottom of the pan, slightly overlapping. I start at the outer edge. If you’re in a hurry or like a more rustic look, you could just randomly cover the bottom of the pan with the sliced plums. Set aside.
The Cake
- In a large bowl, combine the flours, baking powder, baking soda, salt, and cardamom. Set aside.
- In a stand mixer, beat the butter and sugar until light and fluffy, 2-3 minutes.
- Add the almond extract and orange zest and mix until blended.
- Add the eggs one at a time, beating until fully mixed before adding another.
- Reduce speed to low and add half the flour mixture. Beat just until blended.
- Add the sour cream; mix just until blended. Add the remaining flour mixture and beat just until combined.
- Pour the batter over the plums, spreading it out to evenly cover the plums.
- Bake for about 40 minutes. The top should be deep, golden brown and spring back when pressed lightly with your finger. A toothpick inserted in the center will come out clean when it’s done.
- Let the cake cool in the pan on a cooling rack for at least 10 minutes. This is necessary so the topping can “set” somewhat. Run a spatula around the edge before turning the cake over onto a serving plate. Let the cake sit for another minute or two before removing the pan to allow the juices and fruit to loosen from the pan.