This simple cake from 177Milkstreet.com showcases tangy-sweet summertime plums; baked in a solar oven it's both easy and elegant. Both red and black varieties work beautifully. Just make sure to choose ripe, medium plums that still have a little firmness; soft, ultra-juicy fruits will make the center of the cake wet and soggy. Italian prune plums are great, too; use the same weight. But since they are small, cut them into halves instead of quarters.
1 c. all-purpose flour, plus more for pan
½ c white sugar, plus 2 tablespoons for sprinkling
¾ t baking powder
½ t kosher salt
1 stick salted butter, cut into 1-tablespoon pieces, room temperature
1 large egg + 1 egg yolk
1 ½ t. vanilla extract
1 ¼ pounds ripe but firm medium plums, quartered and pitted
powdered sugar, to serve.
Set your Solavore Sport in the sun to preheat; use reflectors if you have them. Mist the bottom and sides of a 9-inch springform pan with cooking spray, then dust evenly with flour; tap out the excess.
In a stand mixer with the paddle attachment, mix the flour, 1/2 cup of the sugar, the baking powder and salt on low until combined, about 5 seconds. With the mixer running, add the butter 1 piece at a time and continue mixing just until the mixture resembles moist sand, 2 to 3 minutes. Add the egg, egg yolk and vanilla. Increase to medium-high and beat until pale and fluffy, about 1 minute, scraping down the bowl as needed.
Transfer the batter to the prepared pan and spread in an even layer. Arrange the plum quarters on top of the batter in 2 concentric circles, placing the pieces on their cut sides. Sprinkle with the remaining 2 tablespoons sugar. Bake until golden brown and a skewer inserted at the center comes out clean. The conventional oven recipe calls for 1 to 11/4 hours at 325º, so in your solar oven with reflector, do the toothpick test at about 2 hours, more or less, depending on the oven temperature.
Let cool in the pan on a wire rack for 30 minutes, then remove the pan sides. Serve warm or at room temperature, dusted with powdered sugar.