Caramelized Plum Upside-Down Cake

With a light rain falling, we arrived early at a local orchard last Sunday. In our enthusiasm, we accidentally picked way too much fruit. Like, nearly fifty pounds too much (!) I looked down the grassy aisle to find my small daughter lugging the giant bucket of peaches she could nearly fit into herself. But, they were so amazing! Peaches! Nectarines! Yellow plums! Dark plums.

On the way home many of the plums had already split in their ripeness. With these we quickly made jam. And then, a plum cake.

The plums are arranged cut side down in a heavily buttered pan, caramelized sugar poured over the top, the batter spread over this before baking. The plums release their juices into the caramel, creating a crimson-colored syrup that sinks into the cake when inverted. The cake itself is soft and buttery.

And now, what to make with the rest...

Plum Cake

The recipe is lightly adapted from Ina Garten, who uses Italian prune plums. Because the red plums I used were clingstone and very soft, I cut along either side of the pit, saving the middle to use in jam-making.

6 tablespoons (3/4 stick) unsalted butter, at room temperature, plus extra for the pan
 10 to 12 small red plums, (or Italian Prune Plums)
1 3/4 cups sugar, divided
 2 extra-large eggs, at room temperature (I had only large eggs on hand)
 1/3 cup sour cream (I used Siggi's 2% yogurt)
 1/2 teaspoon grated lemon zest
 1 teaspoon pure vanilla extract
 1 cup plus 2 tablespoons all-purpose flour
 1/2 teaspoon baking powder
 1/4 teaspoon kosher salt
 confectioners' sugar, for sprinkling

Preheat oven to 350°. Generously butter a 9-inch glass pie dish (I used an 8-inch cake pan). Arrange the plums in the dish, cut side down.

Combine 1 cup of the sugar and 1/3 cup water in a small saucepan and cook over high heat until it turns a warm amber color, about 360° on a candy thermometer. Gently tilt the pan, do not stir (stirring will encourage the formation of sugar crystals). Pour evenly over the plums.

While the sugar is cooking, make the cake batter. Cream the 6 tablespoons of butter and remaining 3/4 cup of sugar in the bowl of an electric mixer fitted with the paddle attachment, until light and fluffy. Lower the speed and beat in the eggs one at a time. Add the sour cream (or yogurt), lemon zest, and vanilla and mix until combined. Whisk together the flour, baking powder, and salt, add to the butter mixture with the mixer on low speed, mixing only until combined.

Pour the batter over the plums, spreading evenly. Bake 30 to 40 minutes until a cake tester inserted in the center comes out clean. Cool for 15 minutes, then invert cake onto serving plate (a plate with a lip helps here, to reign in the juicy caramel). If a plum sticks, gently ease it out and replace it in the design on top of the cake. Serve warm or at room temperature dusted with confectioner's sugar.